I don't think I said that they got than 50% of the vote. But a lot of people voted for them just to be done with Brexit and because they were sick of people in parliament trying to subvert what had been voted for in the referendum.
The number of seats that have always been labour that the conservatives won in order to get the majority weren't won by accident. People voted I think to show what they thought of the MPs who were blocking what they had voted for.
And as I said, on the rare occasion labour win an election they don't worry about their legitimacy because they didn't get more than 50% of the vote.