Thanks!
Wow, thanks for all the quick replies!
Is there a way of checking how much the Avios upgrade would be? I've got a number of flights in the next couple of weeks (Shanghai, Beijing and JFK), but on the booking when I click on 'upgrade with avios), I get the whole,
Sorry, it is not possible to change this booking on ba.com. Please call your local British Airways office to change this booking. message.