Perception is everything
bealine, you may be very right - but if I saw the guy let off the aeroplane before everyone else and shuttled away I would certainly believe s/he did avoid customs. Otherwise, why the special treatment? (and yes, I suppose there that working crew have their own customs formalities - but explain why a BA manager should be entitled to use them?)
And, while it might be treated very seriously if someone was caught - do you really believe that BA would be forced to suspend operations at Heathrow?
I'm sure that the UK Border Agency would see this as being slightly unfair, to penalise BA's customers for a stupid mistake by a BA manager. From the comments in this thread, and in this forum that sounds like the type of decision that BA management would make.
Sorry for the sarcasm, but I don't believe you.