The thing that's changed in recent years is who "owns" the practices. Traditionally they were owned by the senior GPs, they became partners (owners) in the practice they ran.
Now increasingly as older GPs who are partners in prentice's retire they sell their practice to privet equity backed groups. GPs don't want to buy into a practice anymore.
The result of this is significantly worse care and service as the PE backed groups try to extract profits from the system. It's an attractive deal for PE, guaranteed income based on patent list size, and an opportunity to cut costs to make a profit.
Doctor's practices have always been private businesses. It was the NHS that pseudo-nationalized them by making the government the only paying customer (more or less). The doctors recognized the dangers and didn't want it, so Bevin famously had to "stuff their mouths with gold".
IIRC GPs refused to be NHS employees, so the government compromised and agreed to pay existing private GPs to treat NHS patients.