Just want to say thanks to everyone for their advice on this - especially monkeyboy and BUDGIE!
I was late for the interview in Birmingham as trains from London Euston were cancelled that morning (they only announced this as I sat on the damn thing waiting for it to leave) but got there in the end and they seemed quite pleased that I managed to get there at all.
Anyway, after a Belbin psychometric test it was about flying basics, logic and common sense. I think I did all right but who knows.
Good luck to all.