International and IT director, Tesco

Clarke has shot into this year’s power list, following Tesco’s surprise announcement last week that Sir Terry Leahy will step down next year. Clarke, currently international and IT director, will take over as chief executive of the UK’s largest grocer in March 2011.

While Clarke, a Tesco lifer, has big shoes to fill, he has earned his stripes in the international arm, which now accounts for about a third of the grocer’s total sales. One of his greatest achievements was identifying the scale of opportunity in South Korea, with the £958m acquisition of Homever, which has meant Korea is now Tesco’s largest international business.

Clarke, a Liverpudlian like his predecessor, is thought to be cut from the same cloth as Leahy and is aggressive and tough in typical Tesco style. He is thought to be more of a rough-and-ready retailer, rather than a big intellect like Leahy, and doesn’t suffer fools gladly.

Clarke will have his work cut out not only in living up to Leahy’s reign, but in keeping together the top team - many of whom would have been disappointed to miss out on the top job - and maintaining Tesco’s growth.

He will also have to decide on how to tackle its US operation Fresh & Easy, which has lost money for the past three years, but he has signalled that he is committed to that business.