allowed to transfer to T3 on the basis of visiting the American Airlines ticketing desk, one bus an hour for this apparently.
Are these ticketing desks located before or after transfer security when entering T3 by bus?
Because you can catch a intra-terminal bus to any terminal from the T5 connection center without anyone checking your boarding pass. Hence, if the ticket costs are located before security, it is no wonder she get through.
My additional understanding is that the boarding passes are not checked when passing the T3 transfer security checkpoints (when coming in with the intra-terminal bus).
The question would be of course whether CX and QF lounge dragon allow in eligible customers with BA T5 boarding passes. The problem could be in the end that BA may refuse to pay for the access, because it is the wrong terminal.