I agree with what others have said: it's absurd that if one is based in the US one can't book flights ex-LHR from the BA website. Also, since BA is so obsessed with tier points and the whole mess of fare classes, the BA website should at least, as Scott says, allow one to sift through the various fare classes. If one is flying economy (other than full fare) one has no choice but to phone BA to if one wants tier points; booking online you can never be sure what fare class you're getting.