EMBARRASSMENT of a different kind last week engulfed Britain's most celebrated company when BP's boardroom was temporarily transformed into a corporate Big Brother house.Would the impish Lord Browne of Madingley be allowed to stay? Would that big Irish bruiser, Peter Sutherland, bully the board into enforcing a Browne retirement? More astonishing than the dispute itself -the extension of the chief executive's tenure beyond the age of 60- was its public conduct. That such a slick machine as BP should give outsiders a ringside view of a boardroom squabble suggests that this was more than a battle of egos. The truth is that some shareholders are worried about management succession at BP. Over the next two to three years, BP will lose not just Lord Browne but his boardroom nemesis Peter Sutherland and his right-hand man Byron Grote, the inscrutable finance chief. The latter, unlike Browne, has no set retirement date but he is 58, not a contender for the top job and unlikely to remain long after the chief goes.The trouble is that the top job has changed utterly over the past five years and there is no guarantee or even great expectation that BP's smooth succession plan -three or four competing internal candidates- will produce another Browne. When the incumbent took charge 11 years ago, running a big oil company was a job for an engineer with something extra. It was not unlike piloting one of the supertankers in the BP fleet -a lot of technical knowhow plus good management skills-.Politics, strategy and...If BP has thrived over the past decade, it is because its chief executive was more than a talented head of exploration, the post Browne occupied when David Simon was chief executive. Running a major oil company in 2006 is more than anything about politics, strategy and diplomacy. It's about tiptoeing through the minefield of Middle Eastern politics and the corridors of the Kremlin. The best deep-water drilling technology in the world is useful only if the energy minister gives you a permit to drill.BP would argue that it was ever thus -oil has always been found in difficult countries-. However, these difficult countries are no longer rural backwaters but great powers, such as Russia and China. Engineering such deals requires rare finesse.