Thanks for the comments and information, everyone. I hadn't realised there were even more ranges/series than I thought.
Because the figures I've unearthed so far are based, I'm afraid I can't see the codes.
As I haven't used the figures for at least 30 years, I'm still coming across them at the back of drawers and cupboards. So I don't know how many I'll end up with.
I've already based up 20 infantry as a regiment of teenage "Cadets", with figures from the larger current range as taller adult Officers. I was slightly uneasy about the ethics of gaming sending young teenagers into battle but, in the end, accepted it wasn't real life.
BillyNM – I intend to put them on ebay once I know exactly what I have. In the meantime, if you're interested, I can email photos of a few samples to see if it is the series/range you might want. I could put a current Minifig in the photos to give you an idea of the comparative size.
Seeing all the figures I have and the thousands (?) in the Minifig catalogue, and now learning about various other series, I can't but admire the incredible output of the sculptor (I've a vague memory he was called Dick Higgs – or something like that). He must have sculpted several figures every day of his life!
Thanks again.