I tried to get in to the LHR RCC to meet up with a friend last Thursday. I had arrived on AA, he on UA. However am a RCC Lifetime member and 1K. They almost wrestled me to the ground to prevent me from stepping over the threshold. I was given a very curt "Arriving pax are not allowed. Didn't you see the sign...) Well if I'd had seen the sign I would have been less pushy... Needless to say it went downhill from there.
Finally they did offer me a pass to the arrivals lounge which I thought strange since I did arrive on AA..Anything to get rid of me I suppose.
It is not just UA however, AA has the same policy at the Flagship lounge and AC's.
Those quirky Brits I guess.....