I used to work In Practitioner Services - Internal Audit department. I audited the accounts of Inducement Doctors who had to submit their annual expenses so that they could have a top up payment above the normal claims. When I retired the new GP contract was about to be put into place, except for inducement GPs for whom the system was not to change. I must admit I didn't pay much attention after I left - but found this just now, so you could be right about non-salaried GPs. My understanding when I was in teh NHS was that the Practices were to claim fromt eh PCT for all services provided whatever they are, and the GPs were to be paid a salary, but as I said it's along time since I worked there :
This page describes the pay for doctors from 1st April 2009
General practitioners
Many general practitioners (GPs) are self employed and hold contracts, either on their own or as part of a partnership, with their local primary care trust (PCT). The profit of GPs varies according to the services they provide for their patients and the way they choose to provide these services.
Salaried GPs employed directly by PCTs earn between £53,249 to £80,354, dependent on, among other factors, length of service and experience.