I just got into a minor quandry when I thought about 1973 and the existence of lube (as you do.) I think I've mentioned lube in almost all of my stories which feature anal sex. Which is great on the one hand, because, yay, non-self-lubricating arses are love. On the other hand, I suddenly realised I had no idea what lubrication would be used. And it's not that I want to suddenly mention the brand name or anything. I just want to know.
KY wasn't available over the counter in America until 1980 (so, I'm assuming later for Britain.) Astroglide wasn't around.
Would it just be vaseline? Is that usable?
It feels a little silly asking this after over a year of writing Sam/Gene explicit sex, but despite researching all kinds of other things, it never occurred to me that lube might be a sticking point.