Plots that wound but do not kill Brown are perfect for the Tories. They make the voters see Labour as divided and add to the mood that it is time for a change. This one also had the benefit of being ideally timed from a Tory perspective, obscuring a week which had seen Cameron make a rare blunder.
YouGov’s latest poll does show the Tories on course for a majority, no small achievement considering the base they are starting from. But the lead isn’t enough to make any one on the Tory side complacent. If a new Labour leader had had any kind of bounce, Tory jitters about a hung parliament would have become more pronounced.