In 1993 I was "positively vetted" without even knowing, but the rules were different in those days.
I lived in a flat on school premises, and one day I asked whether I needed to be vetted, only to be told that I already had been!
Another very strange one from 2003. A young friend of mine, of Chinese extraction, had put me down as a personal character reference for a job application working in Royal Navy submarines on electronic systems. I was phoned by something along the lines of the "security services," but could not get the precise details, and as they seemed to know that I was a personal character reference, I entered into a three quarters of an hour conversation. Amazingly they only wanted to talk about me and how long I had known my Chineses friend [his parents escaped the Communist in 1948 and used to run a nice Chinese restaurant]. Quite something when you know the Secret Service is taking an interest. I don't suppose they have bothered since!
Up to that time I'd hardly expect to actually ever encounter real "spooks!"
Best wishes from George
PS. An old friend of mine [now deceased] was [at retirement] a director of Turner and Newall, who were major asbestos manufacturers. Earlier in his career he was travelling for the company across Europe and including the Eastern Block as it was. He was approached for duty as a spy. I believe it never went any further ...