Just watch her face at the "bigot' word.

Gillian Duffy is a life-long Labour voter. She doesn't like being called a racist because she worries about immigrants; she's fed up with the welfare state rewarding, as she sees it, the unworthy; she's working class; she's not alone. This is Brown's base. He has essentially attacked his own base in the most condescending two-faced manner possible, on a live microphone, on every broadcast. Imagine if Obama's gaffe about "clinging to guns and religion" had been uttered by John McCain, about his own base. With a week to go.

Now, with Labour in third place already, what will the millions of voters like Duffy do? Vote Tory? I'd like to think so. Maybe immigration will push her to Cameron. But Duffy's obvious belief in the classic Labour welfare state makes me suspect she could protest Labour by voting for the Liberal Democrats. Her initial response is that she won't vote at all - another disaster if replicated for Labour. If millions of Labour voters switch to the Lib-Dems, or stay at home in protest, we are talking about an electoral earthquake of historic proportions. This may be the sound that sets off the avalanche.