National Caving Association has indeed been replaced by the British Caving Association; however, this does not mean there isn't a national caving conservation policy, i.e. a caving conservation policy which has application throughout the country... nationally. The clues are in the words, methinks.
Granted there is reference to the NCA in this (old) document; however, I don't think that changing one word alters the whys and wherefores of good conservation practice.