No Labour or Liberal Democrat conference speech was complete without a reference to Andrew Mitchell's run-in with the police. It began with Vince Cable quipping that he was a "mere pleb" and continued with Danny Alexander greeting Lib Dem delegates as "fellow plebs". For Labour, Ed Miliband angrily denounced Mitchell's behaviour as proof that the Tories could never be a "one nation" government, whilst Yvette Cooper, channeling The Communist Manifesto, cried, "Plebs of the world unite, we have nothing to lose but this Government." And I'd wager that "plebs" will also make an appearance in Harriet Harman's closing speech today.

One can hardly blame them for making play of the incident. Unlike many political scandals, "pleb gate" is easily understood by the public and all the more damaging for it. So damaging, indeed, that Mitchell has pulled out of next week's Conservative conference in Birmingham. The Telegraph reports that the Chief Whip will stay away in order to avoid becoming a "distraction" (which he certainly would have been).

Fortunately for the Tories, Mitchell, as Chief Whip, was not expected to give a speech. Had he remained International Development Secretary in the recent reshuffle, it would have been much harder to justify a non-appearance.