I know, just pointing out that TOR posted it in first place!
It obviously refers to old guidance & only says "recommends", so don't think you need to worry about it (although I have mentioned it to the author):
https://british-caving.org.uk/wiki3/doku.php?id=conservation_access:cave_conservation_code
(Note, it is called just the caving code on website)
NCA was formed in 1968, so only local guidance was available before that, but pretty sure their original code also specified numbers, but can't find a copy.
EDIT - CSCC handbook for 1995 is even more direct : "No less than four in the party".
It obviously refers to old guidance & only says "recommends", so don't think you need to worry about it (although I have mentioned it to the author):
https://british-caving.org.uk/wiki3/doku.php?id=conservation_access:cave_conservation_code
(Note, it is called just the caving code on website)
NCA was formed in 1968, so only local guidance was available before that, but pretty sure their original code also specified numbers, but can't find a copy.
EDIT - CSCC handbook for 1995 is even more direct : "No less than four in the party".