At a hotel in Edinburgh, years ago, the owner moved us guests (mostly American) to a "parlor", as the pub-bar was closing. The doors of the bar were closed, blinds drawn, we noticed when we went outside much later for a walk- but we heard talk. When we came back, we managed a peek through an inside door and saw the room half-full of patrons with their pints. I guess this is what Gareth means by getting a jar after closing time. A couple of days later we were accepted by the owner and joined in.