All the GP practices in England are private businesses working under contract to the NHS. Most people don't notice since the majority of services are covered under that contract.
>>mytail+ib
There are a great many things that the NHS pays practices for on a unit basis which is very much like them seeking payment from an insurer. The system has a far lower administrative cost than the USA model but the contract management process still looks more like a plate of spaghetti and not a circuit diagram.