When Lord Browne, BP chief executive, presented the oil group's annual results to investors in February, he expressed a rising tide of anger over the effect of new accounting standards.

"Some would argue that International Financial Reporting Standards neither produce a record of the accountability of management, nor a measure of the changes in the economic value of assets and liabilities," he said. "I would agree with them. What IFRS actually does is make our results more difficult to understand."