I'm not doing any paid job any more - early retired since 2014.
But in the early summer of 1983 I went through the whole recruitment process for a job as a Firefighter at the Rotherham Eastwood training centre. It was a job I really wanted. Passed the various assessments, the physical (basically running 3 laps of a gym with another candidate in a fireman's lift), the interview, the psychometric tests... the lot. The final stage was a medical. They rejected me on the medical without any explanation - but when I had it re-done through my GP and the local hospital (I was concerned) there was nothing wrong. I suspected I was on an employment blacklist, and the Fire Brigade was outed around that time for using the Economic League blacklist of socialists, communists and active trades unionists. 2 + 2 = 4.
https://en.wikipedia.org/wiki/Econom...nited_Kingdom)
Instead I got a job as a Sheffield bus conductor (in the days of the Socialist Republic of South Yorkshire's low fare policy), and after 3 years of that when the buses all went conductor-free I got a job as a housing officer with the Council. But getting blocked from joining the Fire Serrvice was always a regret.