Whatever the many, many failings of the Labour Party in its present form, we can be absolutely sure that won't be the general reaction from it.
Of course, and this can't be pointed out enough, Labour fairly clearly didn't lose many votes directly to the Tories. The polling looks to have been correct: instead, they suffered serious bleeding to abstentions and to small/minor parties. The electoral system did the rest.
Plus those results in Kensington and the Cities of London and Westminster kinda defy the idea that the British Tories have become a "Trumpist" party. It's still a lot more "respectable" to be a Tory in London than a Republican in Manhattan.