Hullo all.

Some help please.

I'm flying to Bangkok on BA 9 in First on Thursday. Irritatingly, BA 9 is the only flight left with First to operate from T3, meaning that I won't access the CCR (which I've only been in once before but enjoyed hugely), just the Concorde Dining Room if I want to in T3 Galleries First (which I've managed to wangle myself into several times when flying ET).

As it happens, I'm flying to Edinburgh on Thursday morning to see a friend for lunch, flying back in the afternoon to Heathrow before catching my flight at 10pm. The EDI flight is from T5 but, since I don't want to worry about my BKK-bound luggage all day, I'm going to drop it off at T3 first thing in the morning, before my flight to EDI, before heading over to T5 to catch the domestic flight. By dropping off my bag, I will of course have a valid First boarding card for that day's travel. So, when in T5, even though I'm not there to catch the First flight, can I access the CCR? I genuinely have no idea.

To clarify:

c. 5.45am - drop off BKK luggage at T3, collect valid First boarding card
c. 6am - travel to T5, check in and collect valid T5 boarding card
c. 6.10am - TRY TO ACCESS CCR
8am - Flight to EDI
Later - Flight back to LHR
10.05pm - BA 9 from T3 to BKK

Thanks in advance!

Of course I can flash the First boarding pass and hope the lounge guardians don't notice it's for the only BA First flight from a different terminal, but is there an official ruling on this? I can't imagine it happens very often.