Fundholding GPs have the freedom to shop around for the best or most cost-effective treatment and when doctors at the Rowhedge practice became 'dissatisfied' with the Essex Rivers Healthcare NHS Trust they negotiated for their patients to be treated by the Oaks Hospital - one of 10 private units run by a company called Community Hospitals Ltd.
Christine Tarala, a doctor at the practice, said the Essex Rivers NHS Trust could not meet many of the Patient's Charter performance targets and they were forced to refer their patients to the Oaks.
Eileen Smith, 74, a patient with the practice, had a hysterectomy at the Oaks last February. She said: 'I don't care where I was treated - I've paid all my taxes right through life and I've always been treated at the NHS hospital. I don't care how the system works - I just want to be treated. As far as I know, I had the same treatment as in a NHS hospital. They have to look after you, don't they?'
Jonathan Evans-Jones, a consultant at the Oaks, said: 'There's a two-tier system within the NHS whatever the politicians say - I don't know how any politician can stand up and say that it isn't.
'It's not even stretching the truth, it's wrong.
'A good fundholding GP will get his patients into hospital 6-12 months earlier. As a hospital practitioner, I want either all GPs to be fundholders or for none to be. Then we would be back to a one-tier system.'
Mr Evans-Jones said the most aggressive GPs were now able to get their own patients treated sooner, whether in a private or an NHS hospital.
Many GPs were only signing three-month contracts with hospitals, and when the contract came up for renewal it allowed the doctors to re-sign the contract on condition their patients were treated first.
The flow of patients from the Rowhedge practice has prompted the Essex Rivers Trust to be more responsive to patients' demands.
Christina Edwards, director of business development at the trust, said: 'The referral from the Rowhedge practice does affect us. It's part of a trend that we would not like to see continuing.
'We are working with our GP fundholders to try and stop it becoming a trend. We want our service to be responsive to the GPs and to their clients. We are looking at our service and how we can improve it. It's not just the quickness of the service but also it's quality that counts.'