Clegg will not have to deliver his party to Cameron if several of his elected MPs deliver themselves. But if some LibDems look like crossing Clegg might think it expedient to keep his caucus intact by allying his party with the Conservatives. Could work the other way around, of course, but why would a self-interested unprincipled LibDem up-and-comer (I assume there must be one or two like that) want to hitch himself to Brown's tattered coat-tails?