Labour is set to win comfortably. However, the sorts of algorithms they're using to project poll responses to seat numbers just haven't been tested in that extreme. I would treat them all somewhat warily. It's quite possible that the fear of a huge Lab majority could itself persuade people to come out for the Tories on polling day. It's different, of course, but Kinnock's premature triumphalist Sheffied Rally in 92 was enough to persuade people to vote Tory in the last week of campaigning and the give them a blooming working majority.
en.wikipedia.org