An instant poll:

A Times/Populus poll released after the debate showed Mr Cameron defeating Mr Clegg by 37% to 36, with Mr Brown on 27%.

Basically a tie. If Labour slides further into third place, all bets are off. This is by far the least predictable election since 1992. It feels to me like a tectonic plate shifting. That the Liberal Democrats are vying for first place - and have the most appealing potential prime minister and craggiest old chancellor - is gob-smacking. Imagine if Perot had sustained a lead over both Republicans and Democrats. If there's a surge in the youth vote, politics in Britain may change for ever.