OK thanks Globaliser, I was wondering if checking the bags through linked them in some way. You know, thinking back a few years, I have actually had a couple of flights were I was told by both AA and BA due to tropical storm/volcano delays I would have to buy a new flight in London to gla/edi, only to find on arrival BA had actively tracked and rebooked accordingly (even a private car transfer from the air bridge of the arriving AA at T3 to T5 once), and i am sure they were separate cheap Y bookings to Scotland when I think about it. Anyway, enough of my stories, good luck to everyone travelling mon/tues and the festive season in general.