Philip Clarke, the nominated successor to Sir Terry Leahy, the Tesco chief executive who announced his impending retirement on Tuesday, is a bit of an unknown quantity in the City but broker Charles Stanley reckons Clarke's pedigree looks good."Given his already lengthy career at Tesco and success in developing the international business, we consider the appointment to be a good one. We expect his approach to be evolutionary and do not anticipate any radical departures from current strategy," speculated analyst Sam Hart.The broker's recommendation on the stock remains "accumulate", with the supermarket giant's long term earnings growth prospects remaining good, "with International and Tesco Bank likely to be key drivers."