So Allan Leighton, CEO of Wal-Mart Europe, has left the group "to pursue other interests." After eight years at the helm of Asda, one of them under the ownership of Wal-Mart, the world's largest retailer, Leighton claims he's simply had enough. This could be a front for a secret bid to join another UK retailer, but if so, Leighton's playing his cards close to his chest. Both Leighton and Wal-Mart were quick to claim that the parting was mutual and initiated by Leighton, but such statements are almost automatic when senior figures depart.