I frequently visited the Cafe Royal frequently between the ages of seven and 13 (1968 and 1974). My father was a barrister whose chambers were at 47 Peter Street immediately next door.
He would drink large amounts of scotch in the Doubles Bar (tartan wallpaper), which was situated immediately on the left after you went through the revolving door. I sat outside with a coke waiting for him. I also ate in one of the restaurants - there were several on different floors, serving steak, scampi in batter etc. I must have visited the place 50-60 times as a child.