After gaining free entry for years into military establishments, for some reason just before I finished work, I had to be Positively Vetted when there was a change of use of one of them.
I imagine there were a few background checks which I knew little about, but part of the "questionnaire" I had to fill out was details of my 70-year-old "step-fathers' parents (who had both died over 40 years previously).
He wasn't actually my stepfather as my widowed mother married him when I was in my twenties.
However, the information was required and as I had a good relationship with him, he divulged the innocuous details.
I can't for the life of me see how that would have affected my suitability but there you go.
I got "passed" but some time later I was asked by the RAF (sshh) to do some work for them but when they checked my details, BT said I wasn't on their approved list. I was delighted to walk away from what would have been a difficult job and never returned
The strangest one though, was many years ago when there were a lot of checks due to IRA activity.
We used to have to enter a Royal Naval Armaments Depot (sshh) to change air cylinders to pressurise the junction cables (sshh) and one day I went to the control gate and there were new personnel on duty. They asked me why I required entry and once told, they let me through.
I should add that my colleague, who held an Irish passport, was in the passenger seat and they ignored him totally. I suppose we could have been carrying some explosive devices
Hope I haven't divulged any secrets there and am not in danger of investigation from a Guardian reporter.