Thanks for the welcome guys!
And Baz46, I do indeed remember all those areas you mentioned very well.
Kenneth Williams used to live in Great Portland Street. On one occasion, back in 73 I was walking home from school with a classmate, the man himself was walking towards us, it was in Devonshire Street, just outside The Turkish Embassy. He obviously had noticed we'd recognised him, adopted a crouching posture and proceeded to pull comical faces. It really was like a scene from a Carry On film.
After twenty five + years working in London I'd imagine you're a bit of a walking A to Z too!