If the post-debate bounce for the Liberal Democrats persists, history will record one more entry in the long list of reasons to describe the Conservatives as 'the stupid party'.
When the Cameron clique set out to re-brand their faction as akin to the 'nice' Liberal Democrats but more electable, they appear not to have considered the possibility that the electability issue could become fungible. The potential for it increased sharply as soon as the Lib Dem leader was given equal billing in the TV debate, and it came sharply into focus when (so all and sundry appear to agree) Clegg out-pointed his rivals.
By showing a toughness nobody suspected him of possessing - and which is, indeed, underlined by the photo of him on the UKIP poster - Clegg may have broken the game open.
Brown, who it seems spent much of the debate agreeing with Clegg, clearly believes that the Lib Dems can only gain at the expense of the Tories, which will leave Labour as the largest party.
Whether that calculation proves correct or not, it certainly shows more political acumen than the Tories displayed in trying to recast themselves as Lib Dems. Pathetically inadequate though the latter have been during my lifetime, the one thing they are good at is being Lib Dems.
By trying, and failing, to steal Lib Dem clothing, it may be that the Tories have drawn fatal attention to their own ideological nakedness.