TBF several of them have retired, or passed away.
I would include Daleswear; Beaver (diving) still produce a basic caving suit & kneepads, but you rarely see them:
http://www.beaversports.co.uk/Catalogue/Category/156?cat=oversuits
Bernies is now run by ISCA Outdoors from Devon: https://www.berniescaveshop.co.uk/
Not quite sure when this was last updated, but quite some time ago (& do Field & Trek really qualify?):
http://www.arbarama.com/cave/speleo/suppliers.html
Rocksport is nearer 40 years ago. Jo Royale never did much, but is still going in Buxton.
Related threads: https://ukcaving.com/board/index.php?topic=2994.0
& https://ukcaving.com/board/index.php?topic=2996.0
[it would appear Baines was gone by 1979: http://www.classiclightweights.co.uk/baines.html ]