I have once (albeit some years ago) changed planes at MAN. AY->AA. We were force-escorted through the process (we meaning all transfer pax from the AY flight), first to a transfer desk where you get the AA BP and go through the "when did you last send your cell phone to be serviced" interrogation theater, then, when everyone was through, as a group all the way to the gate, without permission to leave the group en route "because there is no time". When we got to the gate, I walked back to the lounge for something to eat and drink and then went to the gate again when the flight started boarding.

All in all, not a nice and smooth process at all. I'm not 100 % sure, but I think it was a BA lounge. No memories about what the lounge was like, though. But if the process is still the same, they're doing everything they can to prevent you from going there.

OT: These escorts are funny sometimes. In December, I changed planes at CDG, also AY->AA. I asked the escort at the gate what the purpose of following him was since I thought there might be some advantage: cutting queues etc. But there wasn't. He just wanted me to stand there (I was seated in row 1) and wait for everyone and then walk with him to AA check-in, because "otherwise you might miss the flight". I smiled at him, assured I won't miss it and told him to just pretend he never saw me and walked away. He looked worried. Then, without all those other pax in tow, I walked to AA F check-in to be interrogated and get my BP and when all was done and I was going to passport control with my priority slip in my hand, I see the escort and the whole herd approaching the Y check-in queue. At that time, I just couldn't resist and had to say to him, "Oh, you're here already!" with a made-up-surprised tone and continued to passport control. I had plenty of time at the CX (!) lounge, too.