DEC Diversified Energy Company PLC

We are selling 8,500,000 of our ordinary shares (£0.20 nominal par value). Our ordinary shares trade on the New York Stock Exchange (“NYSE”) under the symbol “DEC.” On February 18, 2025, the last reported sale price of our ordinary shares on the NYSE was $16.73 per ordinary share. Our ordinary shares are also admitted to listing on the Official List of the United Kingdom Financial Conduct Authority and are admitted to trading on the Main Market of the London Stock Exchange (“LSE”), under the symbol “DEC.” On February 18, 2025, the last reported sale price of our ordinary shares on the LSE was £13.12 per ordinary share (equivalent to approximately $16.54 per ordinary share based on an assumed exchange rate of £1.00 to $1.2607).

We are a “foreign private issuer” as defined under the U.S. federal securities laws and, as such, are subject to reduced public company disclosure requirements. See the subsection titled “Summary—Implications of Being a Foreign Private Issuer” on page S-21 for additional information.

Investing in our ordinary shares involves risks. See “Risk Factors” beginning on page S-32 of this prospectus supplement, page 6 of the accompanying base prospectus, and in the documents we incorporate by reference into this prospectus supplement and the accompanying base prospectus to read about important facts you should consider before buying our ordinary shares.

Neither the U.S. Securities and Exchange Commission (“SEC”) nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying base prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

We have granted the underwriters an option to purchase up to an additional 850,000 ordinary shares, solely to cover over-allotments, at the public offering price set forth above, less the underwriting discount, within 30 days from the date of this prospectus supplement.

The underwriters expect to deliver the ordinary shares to the purchasers on or about      , 2025 through the book-entry facilities of The Depository Trust Company.

For investors outside the United States: Neither we nor the underwriters have done anything that would permit this offering or possession or distribution of this prospectus supplement and the accompanying base prospectus in any jurisdiction, other than the United States, where action for that purpose is required. Persons outside the United States who come into possession of this prospectus supplement and the accompanying base prospectus must inform themselves about, and observe any restrictions relating to, the offering of our ordinary shares and the distribution of this prospectus supplement and the accompanying base prospectus outside the United States.

Neither we nor the underwriters have authorized anyone to provide you with any information or to make any representations other than those contained in or incorporated by reference into this prospectus supplement, the accompanying base prospectus, or in any free writing prospectus we have prepared, and neither we nor the underwriters take responsibility for, and can provide no assurance as to the reliability of, any other information others may give you. Neither we nor the underwriters are making an offer to sell, or seeking offers to buy, these securities in any jurisdiction where the offer or sale is not permitted. The information contained in this prospectus supplement and the accompanying base prospectus, as well as the information we previously filed with the SEC and incorporated herein by reference, is accurate as of the date of those documents only, regardless of the time of delivery of this prospectus supplement or the sale of ordinary shares. Our business, financial condition, results of operations and prospects may have changed since such dates.

This document is not a prospectus for the purposes of the U.K. version of Regulation (EU) 2017/1129 as it forms part of domestic law by virtue of the European Union (Withdrawal) Act 2018, as amended (the “U.K. Prospectus Regulation”) and has not been reviewed and/or approved by the United Kingdom Financial Conduct Authority or any other regulatory authority in the United Kingdom.

No ordinary shares have been offered or will be offered pursuant to the offering to the public in the United Kingdom, except that the ordinary shares may be offered to the public in the United Kingdom at any time:

provided that no such offer of the shares shall require the Company or any underwriter to publish a prospectus pursuant to Section 85 of the FSMA or supplement a prospectus pursuant to Article 23 of the U.K. Prospectus Regulation.

For the purposes of this provision, the expression an “offer to the public” in relation to the ordinary shares in the United Kingdom means the communication in any form and by any means of sufficient information on the terms of the offer and any ordinary shares to be offered so as to enable an investor to decide to purchase or subscribe for any ordinary shares.

In addition, in the United Kingdom, this document is for distribution only to, and is directed only at, and any offer subsequently made may only be directed at persons who are “qualified investors” (as defined in the U.K. Prospectus Regulation) (i) who have professional experience in matters relating to investments falling within Article 19(5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005, as amended (the “Order”), (ii) who are high net worth entities or other persons falling within Article 49(2)(a) to (d) of the Order, or (iii) who are persons to whom an invitation or inducement to engage in investment activity (within the meaning of section 21 of the FSMA) in connection with the issue or sale of any shares of common stock may otherwise lawfully be communicated or caused to be communicated (all such persons together being referred to as “relevant persons”). This document is directed only at relevant persons and must not be acted on or relied on by persons who are not relevant persons. In the United Kingdom, any investment or investment activity that this document relates to may be made or taken exclusively by relevant persons.

The following are abbreviations and definitions of certain terms used in this document:

“2017 Equity Incentive Plan.” The Diversified Gas & Oil plc 2017 Equity Incentive Plan, dated January 30, 2017, as amended and restated on March 29, 2021.

“ABS I Notes.” The notes issued by Diversified ABS LLC pursuant to that certain indenture dated as of November 13, 2019, by and between Diversified ABS LLC, as issuer, and UMB Bank, N.A., as indenture trustee and securities intermediary, as amended.

“ABS II Notes.” The notes issued by Diversified ABS Phase II LLC pursuant to that certain indenture dated as of April 9, 2020, by and between Diversified ABS Phase II LLC, as issuer, and UMB Bank, N.A., as indenture trustee and securities intermediary.

“ABS Warehouse Facility.” The bridge loan facility dated as of June 6, 2024, between DP Mustang Holdco LLC, as issuer, and UMB Bank, N.A., as administrative agent.

“Basin.” A large natural depression on the earth’s surface in which sediments accumulate.

“Bbl.” Barrel or barrels of oil or natural gas liquids.

“Boe.” Barrel of oil equivalent, determined by using the ratio of one Bbl of oil or NGLs to six Mcf of natural gas. The ratio of one barrel of oil or NGLs to six Mcf of natural gas is commonly used in the industry and represents the approximate energy equivalence of oil or NGLs to natural gas, and does not represent the economic equivalency of oil and NGLs to natural gas. The sales price of a barrel of oil or NGLs is considerably higher than the sales price of six Mcf of natural gas.

“Btu” or “British Thermal Unit.” A British thermal unit, which is a measure of the amount of energy required to raise the temperature of one pound of water one degree Fahrenheit.

“Credit Facility.” The Amended and Restated Revolving Credit Agreement, dated as of August 2, 2022, among DP RBL CO LLC, as borrower, Diversified Gas & Oil Corporation, as existing borrower, KeyBank National Association, as administrative agent and issuing bank, Keybanc Capital Markets, as sole lead arranger and sole book runner and the lenders party thereto (as amended to date).

“Drilling.” means any activity related to drilling pad make-ready costs, rig mobilization and creating a wellbore in order to facilitate the ultimate production of hydrocarbons.

“Dry hole.” A well found to be incapable of producing hydrocarbons in sufficient quantities such that proceeds from the sale of such production would exceed production expenses, taxes and the royalty burden.

“Field.” An area consisting of a single reservoir or multiple reservoirs all grouped on, or related to, the same individual geological structural feature or stratigraphic condition. The field name refers to the surface area, although it may refer to both the surface and the underground productive formations.

“Formation.” A layer of rock which has distinct characteristics that differs from nearby rock.

“Gross acres” or “gross wells.” The total acres or wells, as the case may be, in which a working interest is owned.

“Henry Hub.” A natural gas pipeline delivery point that serves as the benchmark natural gas price underlying NYMEX natural gas futures contracts.

“IASB.” The International Accounting Standards Board.

“IFRS.” International Financial Reporting Standards, as issued by the International Accounting Standards Board.

“MBbls.” One thousand barrels of oil, condensate or NGL.

“Mboe.” One thousand Boe.

“Mboepd.” One thousand Boe per day.

“Mcf.” One thousand cubic feet of natural gas.

“Mcfe.” One thousand cubic feet of natural gas equivalent.

“MMBtu.” One million British Thermal Units.

“MMcf.” One million cubic feet of natural gas.

“MMcfe.” One million cubic feet of natural gas equivalent.

“MMcfepd.” One million cubic feet of natural gas equivalent per day.

“NGL” or “NGLs.” Natural gas liquids, such as ethane, propane, butane and natural gasoline that are extracted from natural gas production streams.

“NYMEX.” The New York Mercantile Exchange.

“Oil.” Includes crude oil and condensate.

“Possible reserves.” Possible reserves are those additional reserves that are less certain to be recovered than probable reserves.

“Probable Reserves.” Probable reserves are those additional reserves that are less certain to be recovered than proved reserves but which, together with proved reserves, are as likely as not to be recovered.

“Proved developed reserves.” Reserves of any category that can be expected to be recovered through:

“Proved reserves.” Those quantities of natural gas, NGLs and oil, which, by analysis of geosciences and engineering data, can be estimated with reasonable certainty to be economically producible-from a given date forward, from known reservoirs, and under existing economic conditions, operating methods, and government regulations-prior to the time at which contracts providing the right to operate expire, unless evidence indicates that renewal is reasonable certain, regardless of whether deterministic or probabilistic methods are used for the estimation. The project to extract the hydrocarbons must have commenced or the operator must be reasonably certain that it will commence the project within a reasonable time.

“Proved undeveloped reserves” or “PUDs.” Proved reserves that are expected to be recovered from new wells on undrilled acreage, or from existing wells where a relatively major expenditure is required for recompletion. Reserves on undrilled acreage shall be limited to those directly offsetting development spacing areas that are reasonably certain of production when drilled, unless evidence using reliable technology exists that establishes reasonable certainty of economic producibility at greater distances. Undrilled locations can be

classified as having proved undeveloped reserves only if a development plan has been adopted indicating that they are scheduled to be drilled within five years, unless the specific circumstances justify a longer time. Under no circumstances shall estimates for undeveloped reserves be attributable to any acreage for which an application of fluid injection or other improved recovery technique is contemplated, unless such techniques have been proved effective by actual projects in the same reservoir or an analogous reservoir, or by other evidence using reliable technology establishing reasonable certainty.

“Recompletion.” The process of treating a drilled well followed by the installation of permanent equipment for the production of natural gas, NGLs or oil, in the case of a dry hole, the reporting of abandonment to the appropriate agency.

“Reservoir.” A porous and permeable underground formation containing a natural accumulation of producible natural gas, NGLs and/or oil that is confined by impermeable rock or water barriers and is separate from other reservoirs.

“SOFR.” The Secured Overnight Financing Rate, or SOFR.

“Spacing.” The distance between wells producing from the same reservoir. Spacing is expressed in terms of acres, e.g., 40-acre spacing, and is established by regulatory agencies.

“Standardized Measure.” The year-end present value (discounted at an annual rate of 10%) of estimated future net cash flows to be generated from the production of proved reserves net of estimated income taxes associated with such net cash flows, as determined in accordance with FASB guidelines, without giving effect to non-property related expenses such as indirect general and administrative expenses and debt service or to depreciation, depletion and amortization. Standardized measure does not give effect to derivative transactions.

“Undeveloped acreage.” Lease acreage on which wells have not been drilled or completed to a point that would permit the production of commercial quantities of natural gas, NGLs and oil regardless of whether such acreage contains proved reserves.

“Unit.” The joining of all or substantially all interests in a reservoir or field, rather than a single tract, to provide for development and operation without regard to separate property interests. Also, the area covered by a unitization agreement.

“U.S. GAAP” or “GAAP.” Accounting principles generally accepted in the United States of America.

“Wellbore” or “well.” The hole drilled by the bit that is equipped for natural gas, NGLs or oil production on a completed well. Also called a well or borehole.

“Working interest.” The right granted to the lessee of a property to explore for and to produce and own natural gas, NGLs, oil or other minerals. The working interest owners bear the exploration, development and operating costs on either a cash, penalty or carried basis.

“WTI.” West Texas Intermediate grade crude oil, used as a pricing benchmark for sales contracts and NYMEX oil futures contracts.

Unless another date is specified or the context otherwise requires, all acreage, well count and hedging data presented in this prospectus supplement is as of June 30, 2024, and all reserve-related information is as of December 31, 2023.

This prospectus supplement and the accompanying base prospectus are part of a registration statement that we filed with the SEC using a “shelf” registration process. We provide information to you about the issuance and sale of the ordinary shares offered hereby in separate documents that are bound together: (1) this prospectus supplement, which describes the specific details regarding the issuance and sale of the ordinary shares offered hereby, and (2) the accompanying base prospectus, which provide general information regarding us, our securities, and other information, some of which may not apply to the issuance and sale of the ordinary shares offered hereby. If information in this prospectus supplement is inconsistent with the accompanying base prospectus, you should rely on this prospectus supplement. However, if any statement in one of these documents is inconsistent with a statement in a document incorporated by reference in this prospectus supplement having a later date, the statement in the document having the later date modifies or supersedes the earlier statement as our business, financial condition, results of operations and prospects may have changed since the earlier date.

You should read this prospectus supplement, together with the accompanying base prospectus, the documents incorporated by reference in this prospectus supplement and the accompanying base prospectus and any free writing prospectus that we have authorized for use in connection with the issuance and sale of the ordinary shares offered hereby before making an investment decision. You should also read and consider the information in the documents referred to in the sections of this prospectus supplement and the accompanying base prospectus entitled “Where You Can Find More Information” and “Incorporation of Certain Information by Reference.”

No action is being taken in any jurisdiction outside the United States to permit a public offering of our ordinary shares or possession or distribution of this prospectus supplement and accompanying base prospectus in that jurisdiction. Persons who come into possession of this prospectus supplement and accompanying base prospectus in jurisdictions outside the United States are required to inform themselves about and to observe any restrictions as to this offering and the distribution of this prospectus supplement and accompanying base prospectus applicable to that jurisdiction.

The information appearing in this prospectus supplement, the accompanying base prospectus, the documents incorporated by reference in this prospectus supplement, and in any free writing prospectus that we have authorized for use in connection with the issuance and sale of the ordinary shares offered hereby is accurate only as of its respective date, regardless of the time of delivery of the respective document or of any sale of securities covered by this prospectus supplement. You should not assume that the information contained in or incorporated by reference in this prospectus supplement, in the accompanying base prospectus or in any free writing prospectus that we have authorized for use in connection with the issuance and sale of the ordinary shares offered hereby, is accurate as of any date other than the respective dates thereof.

Except where the context otherwise requires or where otherwise indicated, the terms “Diversified Energy,” the “Company,” the “Group,” “we,” “us,” “our company” and “our business” refer to Diversified Energy Company PLC, together with its consolidated subsidiaries.

For the convenience of the reader, in this prospectus supplement, unless otherwise indicated, translations from pound sterling into U.S. dollars were made at the rate of £1.00 to $1.2607, which was the daily spot exchange rate of the Bank of England on February 17, 2025. Such U.S. dollar amounts are not necessarily indicative of the amounts of U.S. dollars that could actually have been purchased upon exchange of pound sterling at the dates indicated or any other date.

This prospectus supplement incorporates by reference our audited consolidated financial statements as of December 31, 2023 and 2022 and for the years ended December 31, 2023, 2022 and 2021 included in our annual report on Form 20-F for the year ended December 31, 2023, filed with the SEC on March 19, 2024, and prepared in accordance with IFRS, as issued by the IASB, as well as our unaudited interim condensed consolidated financial statements as of June 30, 2024 and for the six months ended June 30, 2024 and 2023 included in our report on Form 6-K furnished to the SEC on August 15, 2024, which have been prepared in accordance with IAS 34 ‘Interim Financial Reporting’, as issued by the IASB, which differ in certain significant respects from U.S. GAAP. None of our financial statements were prepared in accordance with U.S. GAAP.

This prospectus supplement incorporates by reference the audited historical statement of revenues and direct operating expenses for the natural gas and oil properties of OCM Denali Holdings, Inc. (“OCM”) for the year ended December 31, 2023, and the audited consolidated financial statements of Maverick Natural Resources, LLC (“Maverick”) as of December 31, 2023 and 2022 and for each of the two years in the period ended December 31, 2023, each of which were prepared in accordance with U.S. GAAP.

This prospectus supplement includes and incorporates by reference unaudited pro forma condensed combined financial information of the Company as of June 30, 2024 and for the six months ended June 30, 2024 and the year ended December 31, 2023, which such financial information has been derived from the historical consolidated financial statements of the Company, Maverick, and OCM. Since the financial statements of Maverick and OCM were prepared in accordance with U.S. GAAP, while the Company prepares its financial statements in accordance with IFRS, certain adjustments were made to the financial statements of Maverick and OCM in the pro forma financial information to conform to the Company’s IFRS presentation.

The financial information included or incorporated by reference in this prospectus supplement is presented in U.S. dollars. Our fiscal year begins on January 1 and ends on December 31 of the same year.

All references in this prospectus supplement to “$” mean U.S. dollars and all references to “£” mean pound sterling. We have made rounding adjustments to some of the figures included in this prospectus supplement. Accordingly, numerical figures shown as totals in some tables may not be an arithmetic aggregation of the figures that preceded them.

Certain key operating metrics that are not defined under IFRS (alternative performance measures) and GAAP are included in this prospectus supplement. These non-IFRS and non-GAAP financial measures are used by us to monitor the underlying business performance of the Company and Maverick, respectively, from period to period and to facilitate comparison with our peers. Since not all companies calculate these non-IFRS and non-GAAP metrics in the same way, the manner in which we have chosen to calculate the non-IFRS and non-GAAP metrics presented herein may not be compatible with similarly defined terms used by other companies. The non-IFRS and non-GAAP metrics should not be considered in isolation of, or viewed as substitutes for, the financial information prepared in accordance with IFRS or GAAP. Certain of the key operating metrics set forth below are based on information derived from our regularly maintained records and accounting and operating systems. See the sections titled “Summary—Summary Consolidated Financial and Other Data—Non-IFRS and Non-GAAP Financial Measures” in this prospectus supplement for reconciliations of such measures to the most directly comparable IFRS and GAAP financial measures and reasons for the use of such non-IFRS and non-GAAP financial measures.

Adjusted EBITDA. As used herein, EBITDA represents earnings before interest, taxes, depletion, depreciation and amortization. Adjusted EBITDA includes adjusting for items that are not comparable period-over-period, namely, accretion of asset retirement obligation, other (income) expense, loss on joint and working interest owners receivable, gain on bargain purchases, (gain) loss on fair value adjustments of unsettled financial instruments, (gain) loss on natural gas and oil property and equipment, costs associated with acquisitions, other adjusting costs, non-cash equity compensation, (gain) loss on foreign currency hedge, net (gain) loss on interest rate swaps and items of a similar nature.

Adjusted EBITDA should not be considered in isolation or as a substitute for operating profit or loss, net income or loss, or cash flows provided by operating, investing and financing activities. However, we believe such measure is useful to an investor in evaluating our financial performance because it (1) is widely used by investors in the natural gas and oil industry as an indicator of underlying business performance; (2) helps investors to more meaningfully evaluate and compare the results of our operations from period to period by removing the often-volatile revenue impact of changes in the fair value of derivative instruments prior to settlement; (3) is used in the calculation of a key metric in the Credit Facility financial covenants; and (4) is used by us as a performance measure in determining executive compensation. When evaluating this measure, we believe investors also commonly find it useful to evaluate this metric as a percentage of our total revenue, inclusive of settled hedges, producing what we refer to as our adjusted EBITDA margin.

Net Debt and Net Debt-to-Adjusted EBITDA. As used herein, net debt represents total debt as recognized on the balance sheet less cash and restricted cash. Total debt includes our borrowings under the Credit Facility

and borrowings under or issuances of, as applicable, our subsidiaries’ securitization facilities. We believe net debt is a useful indicator of our leverage and capital structure.

As used herein, net debt-to-adjusted EBITDA, or “leverage” or “leverage ratio,” is measured as net debt divided by adjusted EBITDA. We believe that this metric is a key measure of our financial liquidity and flexibility and is used in the calculation of a key metric in one of our Credit Facility financial covenants.

Free Cash Flow. As used herein, Free Cash Flow represents net cash provided by operating activities less expenditures on natural gas and oil properties and equipment and cash paid for interest. We believe that this metric is a useful indicator of our ability to generate cash that is available for activities other than capital expenditures.

Total Revenue, inclusive of settled hedges. As used herein, total revenue, inclusive of settled hedges, includes the impact of derivatives settled in cash. We believe that total revenue, inclusive of settled hedges, is a useful measure because it enables investors to discern our realized revenue after adjusting for the settlement of derivative contracts.

Adjusted EBITDA Margin. As used herein, adjusted EBITDA margin is measured as adjusted EBITDA, as a percentage of total revenue, inclusive of settled hedges. Adjusted EBITDA margin includes the direct operating cost and the portion of general and administrative cost it takes to produce each Mcfe. This metric includes operating expense, employees, administrative costs and professional services and recurring allowance for credit losses, which include fixed and variable costs components. We believe that adjusted EBITDA margin is a useful measure of our profitability and efficiency as well as our earnings quality because it measures the Group on a more comparable basis period-over-period, given we are often involved in transactions that are not comparable between periods.

PV-10. PV-10 of our proved reserves is a non-IFRS and non-GAAP financial measure because it excludes the effects of applicable income tax. We believe that the presentation of the non-IFRS and non-GAAP financial measure of PV-10 provides useful information to investors because it is widely used by professional analysts and sophisticated investors in evaluating natural gas and oil companies. Neither IFRS nor GAAP provides a measure of estimated future net cash flows for reserves other than proved reserves. PV-10 is not a measure of financial or operating performance under IFRS or GAAP. PV-10 should not be considered as an alternative to the standardized measure as defined under IFRS or GAAP. PV-10 differs from the standardized measure of discounted future net cash flows because it does not include the effects of income taxes. Neither PV-10 nor the standardized measure represents an estimate of fair market value of our natural gas and oil properties.

We obtained the industry, market and competitive position data included or incorporated by reference herein from our own internal estimates, surveys and research, as well as from publicly available information, industry and general publications and research, surveys and studies.

Industry publications, research, surveys, studies and forecasts generally state that the information they contain has been obtained from sources believed to be reliable but that the accuracy and completeness of such information is not guaranteed. Forecasts and other forward-looking information obtained from these sources are subject to the same qualifications and uncertainties as the other forward-looking statements in this prospectus supplement. These forecasts and forward-looking information are subject to uncertainty and risk due to a variety of factors, including those described in the sections titled “Special Note Regarding Forward-Looking Statements” and “Risk Factors” found elsewhere in this prospectus supplement. These and other factors could cause results to differ materially from those expressed in the forecasts or estimates from independent third parties and us.

We have proprietary rights to trademarks used in this prospectus supplement or in the documents we incorporate by reference that are important to our business, many of which are registered under applicable intellectual property laws. Solely for convenience, trademarks and trade names referred to in this prospectus supplement or in the documents we incorporate by reference may appear without the “®” or “™” symbols, but such references are not intended to indicate, in any way, that we will not assert, to the fullest extent possible under applicable law, our rights or the rights of the applicable licensor to these trademarks and trade names. We do not intend our use or display of other companies’ trademarks, trade names or service marks to imply a relationship with, or endorsement or sponsorship of us by, any other companies. Each trademark, trade name or service mark of any other company appearing in this prospectus supplement or in the documents incorporated by reference is the property of its respective holder.

This prospectus supplement and the documents incorporated by reference herein and therein contain forward-looking statements that are based on our management’s beliefs and assumptions and on information currently available to our management. Some of the statements under the sections titled “Summary,” “Risk Factors” and “Use of Proceeds” and elsewhere in this prospectus supplement contain forward-looking statements. In some cases, you can identify forward-looking statements by the following words: “may,” “might,” “will,” “could,” “would,” “should,” “expect,” “plan,” “anticipate,” “intend,” “seek,” “believe,” “estimate,” “predict,” “potential,” “continue,” “contemplate,” “possible” or the negative of these terms or other comparable terminology, although not all forward-looking statements contain these words. Forward-looking statements are not guarantees of performance. We have based forward-looking statements in this prospectus supplement on our current expectations and beliefs about future developments and their potential effect on us.

These statements in this prospectus supplement and the documents incorporated by reference herein include, but are not limited to, statements about this offering and the Company’s future plans, expectations, objectives for the Company’s operations, including statements about strategy, synergies, expansion projects, acquisitions and divestitures, future operations; sustainability-related goals, strategies and initiatives, including, among others, those relating our diversity representation targets, reducing methane and greenhouse gas emissions (“GHG”), including our Scope 1 and Scope 2 or net zero goals, environmental management, waste management, safety and asset integrity, health and safety, and community investment and engagement; our plans to achieve our sustainability-related goals and to monitor and report progress; sustainability-related engagement, commitments, and disclosure; and other related items. While this prospectus supplement and the information incorporated by reference herein describe potential future events and matters that may be significant, and with respect to which we may even use the word “material” or “materiality,” the potential significance of these events and matters should not be read as equating to “materiality” as the concept is used in connection with our required disclosures made in response to SEC and exchange rules and regulations.

Any forward-looking statement made by us in this prospectus supplement or incorporated by reference herein speaks only as of the date on which it is made. Factors or events that could cause our actual results to differ may emerge from time to time, and it is not possible for us to predict all of them. Moreover, while the documents incorporated by reference herein may contain information on several sustainability-related topics, including goals and ambitions, there are inherent uncertainties in providing such information, due to the complexity and novelty of many methodologies established for collecting, measuring, and analyzing sustainability-related data. While we anticipate continuing to monitor and report on certain sustainability-related information, we cannot guarantee that such data will be consistent year-to-year, as methodologies and expectations continue to evolve. Additionally, some of the data provided in the documents incorporated by reference herein may be estimated or reliant on estimated information, which is inherently imprecise, and we cannot guarantee that estimates are identified as such in every instance. Furthermore, there are sources of uncertainty and limitations that exist that are beyond our control and could impact our plans and timelines, including the reliance on technological and regulatory advancements and market participants’ behaviors and preferences. We undertake no obligation to publicly update any forward-looking statement whether as a result of new information, future development, or otherwise, except as may be required by law. In some cases, the information in the documents incorporated by reference herein is prepared, or based on information prepared, by government agencies or third-party vendors and consultants and is not independently verified by the Company. Furthermore, unless explicitly noted in each instance where it occurs, the relevant sustainability-related data provided in the documents incorporated by reference herein has not been audited or subject to any third-party assurance process. This data should not be interpreted as any form of guarantee or assurance of accuracy, future results or trends, and we make no representation or warranty as to third-party information.

These statements involve risks, uncertainties and other factors that may cause our actual results, levels of activity, performance or achievements to be materially different from the information expressed or implied by these forward-looking statements. Although we believe that we have a reasonable basis for each forward-looking statement contained in this prospectus supplement and the documents incorporated by reference herein, we caution you that these statements are based on a combination of facts and factors currently known by us and our projections of the future, about which we cannot be certain. Forward-looking statements contained in this prospectus supplement and the documents incorporated by reference herein are inherently subject to significant business, economic, competitive, regulatory and other risks and uncertainties (some of which are beyond our control) and assumptions that could cause our actual results to differ materially from our historical experience

and present expectations or projections. We caution you that assumptions, beliefs, expectations, intentions and projections about future events may and often do vary materially from actual results. Therefore, we cannot assure you that actual results will not differ materially from those expressed or implied by our forward-looking statements. Known material factors that could cause actual results to differ from those expressed in or implied by forward-looking statements contained in this prospectus supplement or incorporated by reference herein are described under “Risk Factors” and in other sections of this prospectus supplement, and in the section titled “Strategic Report—Risk Factors” in our annual report on Form 20-F for the year ended December 31, 2023, filed with the SEC on March 19, 2024, and the risk factors included in Appendix 1 of Exhibit 99.2 in our report on Form 6-K, furnished to the SEC on January 27, 2025, which are each incorporated by reference herein and our other filings with the SEC that are incorporated by reference in this prospectus supplement. Such factors include, but are not limited to:

Reserve engineering is a process of estimating underground accumulations of natural gas, oil and NGLs that cannot be measured in an exact way. The accuracy of any reserve estimate depends on the quality of available data, the interpretation of such data and price and cost assumptions made by our reserve engineers. In addition, the results of drilling, testing and production activities may justify revisions of estimates that were made previously. If significant, such revisions would change the schedule of any further production and development drilling. Accordingly, reserve and PV-10 estimates may differ significantly from the quantities of natural gas, oil and NGLs that are ultimately recovered.

You should refer to the subsection titled “Summary—Summary of Risk Factors” and the section titled “Risk Factors” in this prospectus supplement for a discussion of other important factors that may cause our actual results to differ materially from those expressed or implied by our forward-looking statements. As a result of these factors, we cannot assure you that the forward-looking statements in this prospectus supplement will prove to be accurate.

In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date of this prospectus supplement, and although we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted a thorough inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain, and investors are cautioned not to unduly rely upon these statements. Furthermore, if our forward-looking statements prove to be inaccurate, the inaccuracy may be material. In light of the significant uncertainties in these forward-looking statements, you should not regard these statements as a representation or warranty by us or any other person that we will achieve our objectives and plans in any specified time frame, or at all. We undertake no obligation to publicly update any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

An investment in our ordinary shares involves a high degree of risk. You should carefully consider the risks and uncertainties described below, together with all of the other information included in or incorporated by reference in this prospectus supplement and the accompanying base prospectus, including the section titled “Special Note Regarding Forward-Looking Statements” in this prospectus supplement, and the section titled “Strategic Report—Risk Factors” and our audited consolidated financial statements and related notes, in each case included in our annual report on Form 20-F for the year ended December 31, 2023, filed with the SEC on March 19, 2024, our unaudited interim consolidated financial statements and related notes included in our report on Form 6-K furnished to the SEC on August 15, 2024, and the risk factors included in Appendix 1 of Exhibit 99.2 in our report on Form 6-K, furnished to the SEC on January 27, 2025, which are each incorporated by reference herein, before deciding to invest in our ordinary shares. Additional risks not presently known to us or that we currently deem immaterial may also impair our business operations. Our business, financial condition or results of operations could be materially and adversely affected by any of the following risks or additional risks and uncertainties that are currently immaterial or unknown. The trading price and value of our ordinary shares could decline due to any of these risks, and you may lose all or part of your investment.

The public offering price for the ordinary shares will be determined through negotiations between the underwriters and us, and may vary from the market price of our ordinary shares following this offering. If you purchase ordinary shares in this offering, you may not be able to resell those ordinary shares at or above the public offering price. The market price of our ordinary shares may fluctuate significantly due to a variety of factors, including:

These and other market and industry factors may cause the market price and demand for our ordinary shares to fluctuate substantially, regardless of our actual operating performance, which may limit or prevent investors from readily selling their ordinary shares and may otherwise materially and adversely affect the liquidity of our ordinary shares. In the past, when the market price of a stock has been volatile, holders of that stock have sometimes instituted securities class action litigation against the issuer. If any of the holders of our ordinary

shares were to bring such a lawsuit against us, we could incur substantial costs defending the lawsuit and the attention of our senior management would be diverted from the operation of our business. Any adverse determination in litigation could also subject us to significant liabilities.

Our ordinary shares trade on the NYSE and the Main Market of the LSE. We cannot predict the effect of the dual listing on the value of our ordinary shares, including the extent to which an active market for our ordinary shares in the United States or the United Kingdom will be sustained. However, the dual listing of our ordinary shares may dilute trading liquidity in one or both markets and may adversely affect the further development of an active trading market for our ordinary shares in the United States.

We intend to use the net proceeds from this offering to repay a portion of the debt expected to be incurred by us in connection with the Pending Acquisition. In the event that the Pending Acquisition does not close, we intend to use the net proceeds from this offering to repay debt and for general corporate purposes. The consummation of this offering is not conditioned upon the completion of the Pending Acquisition. We will have broad discretion in the application of the net proceeds from this offering and could spend such proceeds in ways that do not improve our results of operations or enhance the value of our ordinary shares. Our failure to apply these funds effectively could result in financial losses or cause the price of our ordinary shares to decline. Pending their use, we may invest the net proceeds from this offering in a manner that does not produce income or that loses value.

Future sales of a substantial number of our ordinary shares, or the perception that such sales will occur, could cause a decline in the market price of our ordinary shares. Based upon the number of shares outstanding as of December 31, 2024, after giving effect to this offering, we will have 59,795,942 ordinary shares outstanding, approximately 1,621,008 of which will be subject to 30-day lock-up agreements to be entered into by certain of our directors and officers described in the section titled “Underwriting (Conflicts of Interest).” The representatives of the underwriters may, in their sole discretion, release all or any portion of the equity securities subject to the lock-up agreements prior to the expiration of the lock-up agreements. If, after the end of such lock-up agreements, these shareholders sell substantial amounts of ordinary shares in the public market, or the market perceives that such sales may occur, the market price of our ordinary shares and our ability to raise capital through an issue of equity securities in the future could be adversely affected.

We expect the public offering price of our ordinary shares in this offering to be substantially higher than the net tangible book value per ordinary share prior to this offering. Therefore, if you purchase ordinary shares in this offering, you will pay a price per ordinary share that substantially exceeds our net tangible book value per ordinary share after this offering. To the extent outstanding options are exercised for ordinary shares, you may experience further dilution. Based on the assumed public offering price of $    per ordinary share, which reflects the last reported sale price of our ordinary shares on the NYSE on    , 2025, you will experience immediate dilution of $    per ordinary share, representing the difference between our net tangible book value per ordinary share and per ordinary share after giving effect to this and the assumed public offering price. See the section titled “Dilution.”

The decision of our board of directors to recommend and our ability to pay dividends is dependent upon our performance and financial condition, cash requirements, future prospects, commodity prices, compliance with the financial covenants and restrictions under the terms of certain of our credit facilities, profits available for distribution and other factors deemed to be relevant at the time and on the continued health of the markets in which we operate. Further, as a company listed on both the NYSE and the LSE, while our board of directors’

evaluation of our ability or need to pay dividends will primarily remain a question of the foregoing factors, it will also take into account the performance of our ordinary shares, including relative to our peer group. There can be no guarantee that we will continue to pay dividends in the future on our ordinary shares.

The unaudited pro forma condensed combined financial information incorporated by reference in this prospectus supplement are not necessarily indicative of what our actual results of operations would have been for the year ended December 31, 2023 and for the six months ended June 30, 2024 had the Pending Acquisition been completed on the dates indicated, nor are they necessarily indicative of future results of operations for any future period. The unaudited pro forma financial information has been derived from our audited financial statements and the audited financial statements of Maverick and related accounting records, and reflect assumptions and adjustments that are based upon estimates that are subject to change. The purchase price allocation for the Pending Acquisition is preliminary and may change due to several factors, including changes in the estimated fair value of the Maverick properties acquired and liabilities assumed as of the date of the closing of the Pending Acquisition, resulting from the finalization of the Company’s detailed valuation analysis, including changes in future oil and gas commodity prices, reserve estimates, interest rates and other factors. Accordingly, the final acquisition accounting adjustments may differ materially from the pro forma adjustments reflected in the information incorporated by reference into this prospectus supplement, and other factors not presented in such unaudited pro forma financial data may adversely affect our financial condition or results of operations.

We estimate that the net proceeds to us from this offering will be approximately $    million, after deducting the underwriting discounts and commissions and estimated offering expenses payable by us. If the underwriters exercise their over-allotment option to purchase additional ordinary shares in full, we estimate that the net proceeds to be received by us will be approximately $    million, after deducting underwriting discounts and commissions and estimated offering expenses payable by us. We intend to use the net proceeds from this offering to repay a portion of the debt expected to be incurred by us in connection with the Pending Acquisition. In the event that the Pending Acquisition does not close, we intend to use the net proceeds from this offering to repay debt and for general corporate purposes. The consummation of this offering is not conditioned upon the completion of the Pending Acquisition.

We intend to use all of the net proceeds from this offering to repay a portion of any borrowings outstanding under the New Credit Facility at closing of the Pending Acquisition. The New Credit Facility is expected to have similar terms to our existing Credit Facility. The Credit Facility bears interest at a rate of SOFR plus an additional spread that ranges from 2.75% to 3.75% based on utilization and will mature in August 2026. The New Credit Facility is expected to bear interest at a rate of SOFR plus an additional spread that ranges from 2.75% to 3.75% based on utilization and will mature on the fourth anniversary at the closing of the New Credit Facility. Any remaining amount outstanding under the New Credit Facility or, if the Pending Acquisition does not close, the Credit Facility, after application of the net proceeds from this offering will be repaid in accordance with such facility’s terms through a combination of working capital and available banking facilities.

Affiliates of Citigroup Global Markets, Inc. and Mizuho Securities USA LLC are lenders under our Credit Facility and are expected to be lenders under the New Credit Facility at closing of the Pending Acquisition and may receive 5% or more of the net proceeds of this offering to the extent net proceeds are used to repay borrowings under the Credit Facility or New Credit Facility, as applicable. See “Underwriting (Conflicts of Interest)—Conflicts of Interest.”

The following table sets forth our cash and cash equivalents and total capitalization as of December 31, 2024, as follows:

The as adjusted information set forth in the table below is illustrative only and will be adjusted based on the actual public offering price and other terms of this offering determined at pricing. You should read the following table in conjunction with the section titled “Use of Proceeds” elsewhere in this prospectus supplement, and the section titled “Strategic Report—Risk Factors” and our audited consolidated financial statements and related notes included in our annual report on Form 20-F for the year ended December 31, 2023, filed with the SEC on March 19, 2024, and our unaudited interim consolidated financial statements and related notes included in our report on Form 6-K furnished to the SEC on August 15, 2024, which are incorporated by reference herein. Actual amounts are management’s estimates based on financial results of the Company. These amounts have not been audited and are subject to change in connection with the year ended December 31, 2024 audit. Such changes may be material.

If you invest in our ordinary shares in this offering, your ownership interest will be diluted to the extent of the difference between the public offering price per ordinary share and the as adjusted net tangible book value per ordinary share immediately following the consummation of this offering.

At June 30, 2024, we had a historical net tangible book value of $    million, corresponding to a net tangible book value of $    per ordinary share. Net tangible book value per ordinary share represents the amount of our total assets less our total liabilities, excluding goodwill and other intangible assets, divided by the total number of our ordinary shares outstanding.

After giving effect to the sale by us of 8,500,000 ordinary shares in this offering at the assumed public offering price of $    per ordinary share, which reflects the last reported sale price of our ordinary shares on the NYSE on      , 2025, after deducting the underwriting discounts and commissions and estimated offering expenses payable by us, our as adjusted net tangible book value at June 30, 2024 would have been approximately $    million, representing $    per ordinary share. This represents an immediate increase in net tangible book value of $    per ordinary share to existing shareholders and an immediate dilution in net tangible book value of $    per ordinary share to new investors purchasing ordinary shares in this offering at the assumed public offering price. Dilution in net tangible book value per ordinary share to new investors is determined by subtracting as adjusted net tangible book value per ordinary share after this offering from the assumed public offering price per ordinary share paid by new investors.

The following table illustrates this dilution to new investors purchasing ordinary shares in the offering.

If the underwriters exercise their over-allotment option to purchase additional ordinary shares from us in full, our as adjusted net tangible book value per ordinary share after this offering would be $    per ordinary share, representing an immediate increase in as adjusted net tangible book value of $    per ordinary share to existing shareholders and immediate dilution of $    per ordinary share in as adjusted net tangible book value to new investors purchasing ordinary shares in this offering, based on an assumed public offering price of $    per ordinary share, which reflects the last reported sale price of our ordinary shares on the NYSE on    , 2025.

Each $1.00 increase (decrease) in the assumed public offering price of $    per ordinary share, which reflects the last reported sale price of our ordinary shares on the NYSE on    , 2025, would increase (decrease) the as adjusted net tangible book value after this offering by $    per ordinary share and the dilution to new investors participating in the offering by $    per ordinary share, assuming that the number of ordinary shares offered by us, as set forth on the cover page of this prospectus supplement, remains the same, and after deducting underwriting discounts and commissions and estimated offering expenses payable by us. We may also increase or decrease the number of ordinary shares we are offering.

Similarly, an increase of 100,000 in the number of ordinary shares offered by us, as set forth on the cover page of this prospectus supplement, would increase the as adjusted net tangible book value after this offering by $    per ordinary share and decrease the dilution to new investors participating in this offering by $    per ordinary share, assuming no change in the assumed public offering price per ordinary share and after deducting underwriting discounts and commissions and estimated offering expenses payable by us. A decrease of 100,000 in the number of ordinary shares offered by us, as set forth on the cover page of this prospectus supplement, would decrease the as adjusted net tangible book value after this offering by $    per ordinary

share and increase the dilution to new investors participating in this offering by $    per ordinary share, assuming no change in the assumed public offering price per ordinary share and after deducting underwriting discounts and commissions and estimated offering expenses payable by us.

If the underwriters exercise their over-allotment option to purchase additional ordinary shares in full:

To the extent that outstanding options are exercised, new options or other securities are issued under our equity incentive plans, or we issue additional ordinary shares in the future, there will be further dilution to investors participating in this offering. In addition, we may choose to raise additional capital because of market conditions or strategic considerations, even if we believe that we have sufficient funds for our current or future operating plans. If we raise additional capital through the sale of equity or convertible debt securities, the issuance of these securities could result in further dilution to our shareholders.