I was in Birmingham on Thursday. There are three lounges nominally taking PP. One of the - club rooms which is in the corridor with the gates - asks for a mandatory £10 fee on top, the other two are essentially closed unless you book in advance for a fee. At least one of those was not particularly busy when I was there.

Sharp practice IMO, and increasingly common in the UK. Also to note that in Dublin the pay lounge had "at capacity" signs up but was barely being used if you actually went up and they let me in.