Having got distracted by a lightweight tent (its salutary to think I used to fit in that: pre multi-nocturnal trips days),
I have managed to find some parts.
Good news: I have found an unmarked barrel in vgc and what I think is the piston for it (unused).
Bad news: the oil ring is broken.
Intermediate news: I have found an oil ring but I do not know it if fits (and I am not going to try because I have just remembered the last one got broken
)
Steven, you are welcome to pick them up and see if they are any good to you. If so, you owe me a pint.
I am in South Notts.