Originally Posted by
jmcguiga
We are flying JFK to LHR on American Airlines Flagship First in May. Does anyone know if our AA tickets will get us access to the British Airways Concorde lounge?
Welcome to FT
jmcguiga 
So if you are on an AA operated flight from JFK you will depart from terminal 8. BA operated flights and the BA lounges are in terminal 7. As you are in AA F you would have access in T8 to the AA flagship first dining, this is separate and better than the flagship lounge.
Now you can go through security in another terminal, but I think it would be a lot of hassle for you to do that in T7, then exit T7, go over to T8, and go through security there as well. Also I don't believe you would have access to the Concorde room in T7 on the basis of AA F so it would probably be a wasted effort. And tbh with flagship first dining in T8 which you can use, I think that would be at least on a par with what you would get in the Concorde room anyway.