Indeed, it's the old working class vote that Labour is now losing and extending the Conservatives' lead. Staunchly working class areas look at Corbyn and his band of middle-class former (allegedly) Marxists and Communists and see people who have no connection whatsoever with them, hence more are starting to favour the Conservatives.
Of course, only a cynic of the deepest dye would point out the strong correlation between growth of the Tory vote in working class seats and support for Brexit (and the continued strength of the Laboir vote in pro-remain working class seats), or suggest that this may be the result if the Tories' use of Brexit to distract the public from their own incompetence, or wonder what happens when they finally run out of excuses for the pig's ear they have made of the negotiations.
Similarly, only a cynic of the deepest dye would point out tue growing number of members of the aspiring middle class supporting Labour, almost as if they've realised that the Tories, eho are meant to protect theur interests, don't. Only an even more cynical person would point out that, with each passing election, the profile of Tory support moves further and further up the age pyramid.
Anyway, I'm dragging this topic into party political mudslinging, which I'm sure you'd never want to do in a million years.