Opposition leaders are like miniature piglets.They look so sweet in the shop, don't they? With their whiffling little pink noses and their eagerness to please; with their intelligent eyes and their loving natures and the sales assistant's guarantee that they are fastidiously clean and, moreover, will fetch the paper every morning - what's not to love?It is only much later on, well after the election's won and the warranty's expired, that you wake up and realise, with a dull sense of unsurprise, that you've got a six-foot grunter digging up your backyard.