Since you're already living in London, I'd say take BA for sure!!!
From what the interviewer told me there seems to be room for promotion (she told me you have the possibility of being a purser in 4 years) And I think, considering what airline pay is like in the UK, it's one of the best. Definately higher than Virgin Atlantic!
If I was in your position, I'd take BA without a second thought!!!
And I think with the 400 new recruits, morale at BA should be on the up and up!