GPs and other members of the Medical Practitioners' Union (MPU) carried a banner from Embankment to Hyde Park.
Speaking before the event, MPU president and retired GP Dr Ron Singer said: ‘MPU doctors are continuing the fight for an NHS, oppressed by the new Health Act, keeping its core values of a comprehensive service free at the point of delivery.
‘MPU believes that the Health Act is bad news for the NHS. GPs are being used by the government to mis-inform the public that the NHS will be run by clinicians and will be designed "by the people that know you best, your GP".’
Dr Singer added: ‘Doctors have a clear duty to speak out when services for patients are threatened. It is now crystal clear that cut backs are beginning to have an effect on waiting times in A&E and for operations and that some PCTs, before they are abolished, are restricting important operations for conditions such as cataracts, hips and knees.’