When I leave this stage for the last time on Thursday, I will be bowing out of medicine and medical politics for good.

The one memory that will linger long after the sweet taste of negotiating successes and the sour taste of acid encounters with self-serving secretaries of state for health have left my palate is the creeping, morale-sapping erosion of doctors' clinical autonomy, brought about by micro-management from Whitehall which has turned the NHS I hold so dear into the most centralised public service in the free world.

The stifling of innovation by excessive, intrusive audit and the imposition of Department of Health diktats; the shackling of doctors by prescribing guidelines, referral guidelines and protocols; the suffocation of professional responsibility by target-setting and production-line values that leave little room either for the professional judgement of individual doctors - or for the needs of individual patients

No doctor has any trouble signing up to genuine, evidence-based efforts designed to drive up standards and to improve the quality of services to patients.

But the paranoid centralism that has characterised this and previous governments' handling of the National Health Service will not lead to improvements in patient care. It will turn healthcare professionals into bean counters answerable not to their patients but to politicians, auditors, commissioners and managers under pressure to deliver on edicts, priorities and targets emanating from Richmond House (where the headquarters of the Department of Health is based).

I'm nearing the end of a 40-year career in medicine - a career that I have loved and from which I have drawn enormous personal and professional satisfaction.

Nothing comes close to the unspoken but absolute trust that exists between patient and doctor, to the privilege of being let into people's lives and people's thoughts, to the patient who says, 'Thank you doctor, that helped.'

But when I look back over my career and how the practice of medicine has changed during that time, there is one thought I cannot shake from my mind. The challenge, the responsibility, the risk that I relished, and that I regarded as being fundamental to my professional status, have all but disappeared.

When I first went into practice against the wishes of my father, who was a doctor himself but wanted me to be a dentist because the pay was better, I wasn't interested in financial rewards. I wasn't interested in adulation from awe-struck patients or in being hero-worshipped by nubile young nurses. I wasn't interested in achieving immortality as the discoverer of some rare and exotic disease.

The reason that I became a doctor was because I wanted to help people who were ill or who were in distress. I remember that I earned £9 a week and that I was on duty for four nights out of seven.

My motivation and my satisfaction came from knowing that I was able to apply my knowledge and exercise my judgement free from control or interference from outside the consulting room.

I felt free, and safe, to do what I thought was best for those in my care.