Re: I still have some pairs of trousers that are that old
"I have some early 90s vintage swimming trunks (albeit bought as NOS about 10 years back)"
I have a Jantzen pair that I bought in 1972 - even have the Standard 8 film of me wearing them. A fashionable improvement on my woollen ones that hung to the knees when full of water.
My Fred Perry short shorts (70s?) were all bought on ebay. In excellent condition - their owners had probably hoped one day to diet enough for them to fit again. They actually came back into fashion a couple of years ago. School kids stopped singing "we like short shorts" as we passed in the street - and now wanted to know where they could buy them.