All the new young people who are coming to vote, surely it also depends on their locations? In Woking for example, 10,000 youngsters suddenly voting for labour wouldn't even half their deficit to the tories based on the 2015 result.
edit: double quote by accident
I am only going on what i read and maybe that is a failing of the computer model, based purely only demographic rather than majorities held in certain seats.
I'm literally not clever enough to work out how they do this stuff, I just have to hope that they're right