Dave Cameron's chances of winning an overall majority at the next election don't just depend on taking seats off Labour, but reclaiming former Conservative seats from the Liberal Democrats.
He may soon have a chance to show what he can do. Mark Oaten was at one time a potential party leader, but his career was damaged by a rent boy scandal. He was planning to stand down at the next election anyway, but may go early to take up a job opportunity.
Although his majority of over 21,000 may appear to be cast iron, it was obtained in a by-election after the Conservatives have overturned the original result in the courts. Winchester was once a solid Conservative seat and Dave will be hoping to take it back. If he can, it will be a further boost to his chances of success at the next general election.