Fraser Nelson weighs in:
We have just witnessed the biggest moment of the 2010 election campaign. It wasn't that Brown let off steam: it was that he instinctively described as "bigoted" a woman who represents what should be Labour's core vote. Sure, she mentioned immigration - but just said "where are they coming from"? Her main concern was the national debt, and what her grandchildren will have to pay. Neither Cameron or Clegg would have thought these points bigoted - and neither would Tony Blair.
It is of course manna from heaven for the media. A new character. An encounter that will be played again and again on TV, not just in Britain but around the world. And something which absorbs all the space in the debate that Labour had been hoping might move to policy, and moves the focus to questions of character.
...I saw [Brown] at his Manchester hotel, where we are preparing for tomorrow's debate, when he returned from Rochdale. To say he was mortified is an understatement. I don't think I have ever seen him so angry with himself. And he was angry less about the obvious frenzy he had unleashed than the fact that he said what he did. She was so clearly not a bigot, and he knew that.