Tried to access the BA lounge at Terminal 5 using my Qantas Club card but got refused, the door nazi had a laminated card which said Qantas Club didn't get you access.
Checking the Qantas website, my interpretation is I should've been allowed in ...
In addition to Qantas Club lounges, you can relax in British Airways lounges (Terraces and Executive Club lounges) and American Airlines® Admirals Club lounges.
To access a partner airline lounge, simply present your Qantas Club card or Platinum or Gold Frequent Flyer card at check-in and again with your boarding pass at the lounge reception. You may also invite a guest. Note: both you and your guest must be travelling together and have onward travel that day on a flight marketed and operated by the partner airline whose lounge you wish to visit
... what have I misinterpreted. The fact that the BA staff had a laminated card they could stuff in my face suggests I wasn't the first person to try.