Raiding the Labour Vote

David Cameron and the Conservatives did very well in the British election, so why couldn't they win Gillian Duffy's vote?

Okay, after reading everything I can get my hands on about the British elections, I'm coming to some conclusions.

1) By a bunch of the more esoteric measures ("net new votes gained", etc.), David Cameron did a pretty okay job, considering.

2) The glaring opportunity left for the Conservatives is to increase their share of the popular vote.  The anti-Cameron Tories (including the ones on our side of the pond editing magazines and such) are wrong about a lot of things, but they are right that that was the weakness.

3) Increasing the vote share is going to require either raiding Labour voters, or LibDem voters.  Cameron has maxed out on conservative voters and newer voters.

4) Since the governing alliance is going to be with the LibDems, then it's the lightly-affiliated Labour voter that'll have to be targeted next time around.

5) So the question that I'm asking when it comes to the Labour vote: why wasn't Cameron able to make hay out of Gordon Brown's "bigoted woman" comment?

No, I don't mean doing like John McCain mentioning Joe the Plumber 18,000 times.  David Cameron wouldn't have had to mention Gillian Duffy's name at all.  In fact, I don't think he needed to talk about Gillian Duffy's concern -- immigration -- more than he did.  But was there some way to indicate better that the Conservatives needed and deserved Gillian Duffy's vote? Because if Cameron wanted to get from 36% to 39%, I think he did.

Gordon Brown sent her flowers; did David Cameron? Will he do so next time?