Saw the story before I think The Guardian picked it up. I will have to search.
It isn't NHS charging but NHS GPs deciding to run a private practice in their NHS surgery. They are allowed to do that even though it is considered unethnical by many.
A GP practice walking distance from me (not my GP) actually has a floor of rooms underneath them which physios and other private practitioners can hire out. However they currently don't allows other GPs to hire out the rooms.
Anyway the GPs aren't suppose to treat their own patients privately as it is a conflict of interest.