Additionally, the UK mostly has "closed" gaterooms which require handling agent staff to check the passengers boarding passes and passports before letting them into the gateroom (in the US they have open gaterooms and the checks are done just as passengers board).
Is this true nowadays? What airports still have them? LHR has some at T3 after T2B was so build then changed to open plan. I think LGW has them on on Pier 2 only nowadays since North was refurbished. Any others still in existence?