Thanks. Actually, as I'm trying to stick to e-tickets, I don't actually need to visit anybody and it's easiest to do by email, or over the phone. Sounds like the BA RTW desk would be my best option - thanks for that number
I just called them, and for the benefit of others, they are open 0800-2000EST, but unfortunately do not have a regular (non-800) number which can be called from overseas.