Well we'll just all have to wait and see. A possible upset certainly would make a fun election night, and the Conservatives can't really get much deeper in the hole than they already are (for the most part). If Labour has a net gain of seats, I'll eat a shoe.
I do not believe that Labour will gain seats tonight - there's no reason for gains. People, generally speaking, are tired and unenthusiastic about Labour.
Regards, Ivan