Thanks PatD. and Jethro, It's nice to know I hadn't gone completely bongo !!

Seriously, I know what I saw and I stared for a long time.However I may have got the year wrong. It was probably further into the eighties than I previously stated.

I said "medallion " but it wasn't a normal neat ,round one but-as I remember-rough-hewn in an arty/crafty way , very thick, and very gold.

I don't remember seeing a crown ( and I think I would have ! ). I suppose that would have drawn a lot of attention in the middle of the window especially if it was of  unspecified origin !