Parts were certainly much easier to get back then, civilian semi automatic military rifles were always a relatively small part of the UK shooting scene, but several dealers specialised in supplying rifles and parts.

The vast majority were Lithgowicon (including a few semi automatic converted Malay L2A1's) , but mixed in with that were a number of semi automatic converted Fal's and a good number of Ishapore 1A1's.

I've had deactivated examples of all the above go through my hands over the years.

I've heard of a few Britishicon examples in civilian ownership, but yet to see any evidence of that.

Due to the trickle of Straight pull L1A1's being available, by 'far' the best by Peter Sarony, there's actually a good number of BSA L1A1's (a few hundred at least), some Lithgow's and a very small number of Enfield made examples, though some of these are mixmaster reciver and TMH's..