When I left the RAF in 1983 after nine years service I had no knowledge of preserved pensions, I thought if you left before 22 you got nothing. It was only decades later that I heard something from people currently serving that I started asking questions.
If I hadn't met those people I would never have known, I wonder how many other people are in the same boat?
My brother-in-law (12 years army) didn't know either.