Over the last year every thread on UKIP or tory voters has been 80% name calling. Over and over people have called them idiots, racists, disablist and worse. Any attempt to discuss calmly any potential valid concerns were met with vitriol. Even post the election, most of the commentary has been that the electorate were duped or that they were evil cunts.
AIBU to think that this is part of the problem? It turns out that when you name call, people are quiet - but don't change their views! UKIP are wrong - 100%. But people had fears and concerns about the future of the country and instead of engaging with them, the left made them feel ashamed and told them to shut up. So they went to UKIP and they abandoned Labour.
I think a big issue and very prominent on mumsnet is that the anti-fascist working class seems to despise (what they perceive to be as) the "softly pro fascist" working class. There seems to be huge contempt on the basis that "we grew up similarly and I didn't fall for it". They have the evangelical zeal of ex smokers. But not everyone is you. And you have to meet people where they are, not where you want them to be.
You can't win people without respecting them. Part of respecting them is listening to them. (John Harris at the Guardian is actually pretty good on this.) Labour will not win again until they realize that.