Does LHR not have VIP facilities for checking in/clearing security/passport control etc? I am surprised that she cannot be "serviced" somewhere away from the scrum. Do all VIPs or PWTTAVIPs go through the normal security channels?

Assuming they do, then I think it is entirely appropriate that they be led "discretely" to the front of the queue. And I think it would be good practice and a simply courtesy to mutter an "excuse me" or something similar, to BA's most loyal customers, that possibly spend more money flying BA every year that she does.

May be spends more, but that's not the point. This is Britain. And when you queue jump, you mutter an embarrassed and apologetic "excuse me".