Assurance and standards

Independent assurance report to Tullow Group Services Limited on the Tullow Oil plc 2009 Corporate Responsibility Report (“the Report”)

Scope of assurance work

We have been engaged by the Board of Directors of Tullow Group Services Limited to perform limited assurance¹ procedures on Tullow Oil plc’s (“Tullow Oil”) Group level compilation of its environmental, safety, social and social enterprise expenditure performance indicators (marked with *) for the financial year ending 31 December 2009.

Basis of our assurance work and our assurance procedures

We carried out limited assurance in accordance with the International Standards on Assurance Engagements 3000 (ISAE 3000). To achieve limited assurance the ISAE 3000 requires that we review the processes and systems used to compile the areas on which we provide assurance. It does not include detailed testing of source data or the operating effectiveness of processes and internal controls. This provides less assurance and is substantially less in scope than a reasonable assurance¹ engagement.

The evaluation criteria used for our assurance are Tullow Oil’s definitions and basis of reporting the indicators described on www.tullowoil.com/cr09

Considering the risk of material error, a multi-disciplinary team of corporate responsibility and assurance specialists planned and performed our work to obtain all the information and explanations we considered necessary to provide sufficient evidence to support our assurance conclusion. Our work was planned to mirror Tullow Oil’s own Group level compilation processes, tracing how data for each indicator within our assurance scope was collected, collated and validated by Group head office and included in the Report.

Our work was based at head office and involved reviewing data collection, collation and validation at Group level only.

Our assurance conclusion

Based on the assurance work performed, nothing has come to our attention to suggest that the description in Tullow Oil’s basis of reporting for the compilation of the environmental, safety, social and social enterprise performance indicators (marked with *) are materially misstated.

Responsibilities of Directors and independent assurance provider

The Directors are responsible for the preparation of the Report and statement contained within it. They are responsible for determining Tullow Oil’s objectives in respect of environmental, safety, social and social enterprise performance and for establishing and maintaining appropriate performance management and internal control systems from which the reported information is derived.

Our responsibility is to independently express conclusions on reliability of management’s assertions on the selected subject matters as defined within the scope of work above.

We performed the engagement in accordance with Deloitte’s independence policies, which cover all of the requirements of the International Federation of Accountants (IFAC) Code of Ethics and in some areas are more restrictive. We confirm to Tullow Group Services Limited that we have maintained our independence and objectivity throughout the year, including the fact that there were no events or prohibited services provided which could impair that independence and objectivity in the provision of this engagement.

This Report is made solely to Tullow Group Services Limited in accordance with our letter of engagement for the purpose of the Directors’ governance and stewardship. Our work has been undertaken so that we might state to the Company those matters we are required to state to them in this report and for no other purpose. To the fullest extent permitted by law, we do not accept or assume responsibility to anyone other than Tullow Group Services Limited for our work, for this report, or for the conclusions we have formed.

Deloitte LLP
London, 17 May 2010

¹The levels of assurance engagement are defined in ISAE 3000. A reasonable level of assurance is similar to the audit of financial statements; a limited level of assurance is similar to the review of a half year financial report.