Upgrades are done by QFF Status level. "Chairman's Lounge"* and/or Platinum One, then Platinum, then Gold then Silver then Bronze.

You can request upgrades be fulfilled right up to boarding time when you request an upgrade.

You can try showing your BA/AA Emerald card at the First entrance and they may permit you entry. They also may insist on putting the Emerald status into the booking. (Qantas have this policy for non oneworld entry, but many lounge agents confuse this and apply it to everyone.) By that time you are likely to have been upgraded or not in any case.


*Sort of Equivalent to Concierge Key.