Harbour Energy : Appendix

Harbour Energy plc

#WeAreHarbourEnergy

External review of our ESG reporting

Verisk Maplecroft was commissioned by Harbour Energy plc to:

• ƒ Conduct an ESG materiality assessment to help inform the ESG content of Harbour Energy's 2022 ESG Report (see below).

• ƒ Support the overall content development of Harbour Energy's 2022 ESG Report, and its alignment to the GRI Standards and other applicable standards (see below).

• ƒ Ensure the accuracy of disclosures made against material ESG topics in Harbour Energy's 2022 ESG Report.

This statement is made in our capacity as an ongoing service provider to Harbour Energy on this assignment. Verisk Maplecroft did not directly verify the data relating to the Environment, Safety, Social and Governance (ESSG) aspects of the report. We did, however, confirm the existence of Harbour Energy policy statements, the veracity of management systems and the rigour of internal reporting/review processes.

Methodology

Verisk Maplecroft's review of Harbour Energy's ESG performance involved the following activities between September 2022 and March 2023:

• ƒ Internal engagement: This included interviewing subject matter experts across key disciplines (including HSES, human resources, legal, audit and risk management, investor relations, and others)

  at both Group level and business unit level, to gather information for the 2022 ESG Report and to update scoring for the materiality assessment process.

• ƒ Standards and recommendations: This included supporting Harbour Energy with the alignment of its 2022 ESG Report to international best practice reporting standards and recommendations. These standards included (1) GRI Standards (including the latest GRI 11: Oil and Gas Sector 2021 Standard); (2) UN Global Compact Principles; (3) Task Force on Climate-related Financial Disclosures (TCFD); and (4) Sustainability Accounting Standards Board (SASB).

• ƒ In addition, our work involved engagement with Harbour Energy on the potential for further public reporting to meet the emerging expectations of external stakeholders.

• ƒ Materiality assessment process: Verisk Maplecroft assisted Harbour Energy with the scoring and outputs of its structured materiality assessment process to help identify its material ESG issues. This included engaging with internal and external stakeholders. The overall process is aligned with the requirements of the GRI Standards.

• ƒ Gap analysis: A high-level gap analysis was carried out to identify and, where feasible, address gaps in Harbour Energy's existing reporting practices.

• ƒ Performance enhancement: The outcomes from the review of standards and gap analysis were used, where possible, to enhance Harbour Energy's level of reporting.

Materiality and completeness

Verisk Maplecroft believes that the narrative and data presented in this report are an accurate representation of Harbour Energy's material ESG issues. Verisk Maplecroft is also satisfied that Harbour Energy's

GRI Core 'in-accordance' claim is fairly stated. Harbour Energy has reported on its management approaches towards its material issues and on relevant disclosures.

JAMES ALLAN

VP, HEAD OF CONSULTING

10 MARCH 2023

VERISK MAPLECROFT, 1 HENRY STREET, BATH BA1 1JS, UNITED KINGDOM

Independent assurance statement

ERM Certification & Verification Services Limited ('ERM CVS') was engaged by Harbour Energy Plc ('Harbour') to provide limited assurance in relation to the selected information set out below and presented in Harbour's ESG Report 2022 (the 'Report').

Engagement summary

Scope of our assurance engagement

Whether the following 2022 selected information are fairly presented in the Report, in all material respects, in accordance with the reporting criteria:

• ƒ 11.1.2 (302-1 Energy consumption within the organisation)

• ƒ 11.1.3 (302-2 Energy consumption outside of the organisation)

• ƒ 11.1.4 (302-3 Energy intensity)

• ƒ 11.1.5 (305-1 Direct (Scope 1) GHG emissions)

• ƒ 11.1.6 (305-2 Energy indirect (Scope 2) GHG emissions)

• ƒ 11.1.7 (305-3 Other indirect (Scope 3) GHG emissions - Category 1 (Purchased goods and services), Category 4 (Purchased Goods and Services), Category 5 (Waste), Category 6 (Business travel) and Category 15 (Investments) only.

• ƒ 11.1.8 (305-4 GHG emissions intensity)

• ƒ 11.3.1 (305-7 Nitrogen oxides (NOx), sulphur oxides (SOx), and other significant air emissions)

• ƒ 11.5.2 (306-1 Waste generation and significant waste-related impacts)

• ƒ 11.5.3 (306-2 Management of significant waste-related impacts)

• ƒ 11.5.4 (306-3 Waste generated)

• ƒ 11.5.5 (306-4 Waste diverted from disposal)

• ƒ 11.5.6 (306-5 Waste directed to disposal)

• ƒ 11.6.4 (303-3 Water withdrawal)

• ƒ 11.6.5 (303-4 Water discharge)

• ƒ 11.6.6 (303-5 Water consumption)

• ƒ 11.8.2 (306-3 Significant spills)

• ƒ 11.8.3 (Tier 1 and Tier 2 process safety events)

• ƒ 11.9.10 (403-9 Work-related injuries)

Our assurance engagement does not extend to information in respect of earlier periods or to any other information included in the Report.

Reporting period

1st January 2022 - 31st December 2022

Reporting criteria

GRI 11: Oil and Gas Sector 2021 (including applicable GRI Topic Standards)

Assurance standard and level of assurance

We performed a limited assurance engagement, in accordance with the International Standard on Assurance Engagements ISAE 3000 (Revised) 'Assurance Engagements other than Audits or Reviews of Historical Financial issued by the International Auditing and Standards Board.

The procedures performed in a limited assurance engagement vary in nature and timing from, and are less in extent than for a reasonable assurance engagement and consequently, the level of assurance obtained in a limited assurance engagement is substantially lower than the assurance that would have been obtained had a reasonable assurance engagement been performed.

Respective responsibilities

Harbour is responsible for preparing the Report and for the collection and presentation of the information within it, and for the designing, implementing and maintaining of internal controls relevant to the preparation and presentation of the selected information. ERM CVS' responsibility is to provide conclusions to Harbour on the agreed scope based on our engagement terms with Harbour, the assurance activities performed and exercising our professional judgement. We accept no responsibility, and deny any liability, to any party other than Harbour for the conclusions we have reached.

Independent assurance statement continued

Our conclusion

Based on our activities, as described below, nothing has come to our attention to indicate that the selected 2022 information listed under 'Scope' above are not fairly presented in the Report, in all material respects, in accordance with the reporting criteria.

Our assurance activities

Considering the level of assurance and our assessment of the risk of material misstatement of the selected information, a multi-disciplinary team of sustainability and assurance specialists performed a range of procedures that included, but was not restricted to, the following:

• ƒ Assessing the appropriateness of the reporting criteria for the selected performance data.

• ƒ Interviews with management representatives responsible for managing the selected issues.

• ƒ Interviews with relevant staff to understand and evaluate the relevant management systems and processes (including internal review and control processes) used for collecting and reporting the selected disclosures.

• ƒ A review at corporate level of a sample of qualitative and quantitative evidence supporting the reported information.

• ƒ An analytical review of the year-end data submitted by all locations included in the consolidated 2022 group data for the selected information which included testing the completeness and mathematical accuracy of conversions and calculations, and consolidation in line with the stated reporting boundary.

• ƒ Confirming conversion and emission factors and assumptions used.

• ƒ Reviewing the presentation of information relevant to the scope of our work in the Report to ensure consistency with our findings.

The limitations of our engagement

The reliability of the assured information is subject to inherent uncertainties, given the available methods for determining, calculating or estimating the underlying information. It is important to understand our assurance conclusions in this context.

Our independence, integrity and quality control

ERM CVS is an independent certification and verification body accredited by UKAS to ISO 17021:2015. Accordingly we maintain a comprehensive system of quality control, including documented policies and procedures regarding compliance with ethical requirements, professional standards, and applicable legal and regulatory requirements. Our quality management system is at least as demanding as the relevant sections of ISQM-1 and ISQM-2 (2022).

ERM CVS applies a Code of Conduct and related policies to ensure that its employees maintain integrity, objectivity, professional competence and high ethical standards in their work. Our processes are designed and implemented to ensure that the work we undertake is objective, impartial and free from bias and conflict of interest. Our certified management system covers independence and ethical requirements that are at least as demanding as the relevant sections of Parts A & B of the IESBA Code relating to assurance engagements.

The team that has undertaken this assurance engagement has extensive experience in conducting assurance on environmental, social, ethical and health and safety information, systems and processes, and provides no consultancy related services to Harbour in any respect.

PARTNER, CORPORATE ASSURANCE LONDON, UNITED KINGDOM

7 MARCH 2023

ERM Certification and Verification Services Limitedwww.ermcvs.com| post@ermcvs.com

Harbour Energy plc ESG Report 202257