Aware that the K.C owns (?) Breed Standards within the UK, but who sets/defines those standards the Breed Clubs or the K.C?

Breed Council.

So when changes are made to standards, is this initiated by the K.C, Breed Clubs or Breed Council?

It will be breed clubs who take it to the breed council, who then take it to the KC. My breed has 11 breed clubs which is why we have a breed council(I believe), I am not sure if all breeds have a breed council.

The Breed Club executive, I think/hope in agreement with the various more local BH Breed Clubs around the country - with the recent amendmends to the BH Standard, amendments were made to try to rule out the 'exaggerations' that had crept into the breed.  The amendments were then ratified by the KC.   Again in the case of the Basset, after the breed went on the 'at risk' list (mainly re eyes), I'd imagine the Club executive knew they had to do something to get the breed sorted out and off that list.   I can't talk for any other breed although I do know similar happened with the Bloodhound, again re the excessive haw in the breed.

Thank you both, had always thought the breed club set the standard, had forgotten there would be a number of clubs within breeds.