That is the real test for clinical governance and revalidation measures

Harold Shipman's cunning and secretive determination would have tested any system of professional regulation. But even allowing for the singular nature of his crimes and their extravagant scale, his actions have exposed GP regulation as inadequate and attitudes towards it as lax and complacent.

Before he was arrested, the proposition that a GP might serially murder patients - estimates of the number of Dr Shipman's victims currently range from 150 to 1,500 - was unconscionable. What is more, Dr Shipman was in many respects a pillar of the medical community: he had been a fundholder, secretary of the local medical committee, member of the community health council and stalwart of the Small Practices Association. His single-handed practice was popular with patients. Hardly obvious credentials for admission to the front rank of Britain's mass murderers; indeed, likely to deter the curious from posing awkward questions for fear of goading the wrath of the establishment.

Yet there were signs aplenty that something was amiss with the way Dr Shipman practised medicine: high death rates among elderly women patients, and the manner of their deaths; the high number of deaths which took place in his surgery; the number of cremation certificates he requested. He was also recognised as a high prescriber, and monitored accordingly. But these separate, though related clues were never pieced together for vigorous scrutiny and challenge - despite the suspicions of a local undertaker, a fellow GP and the coroner.

One vital indicator of Dr Shipman's instability might have tempted an earlier and more thorough probe by putting his practice characteristics in a different perspective: his conviction for drug abuse in 1976. Yet 20 years later, this brush with the courts and the General Medical Council had been effectively expunged from his CV. That should never happen again. Without detracting from the potential for rehabilitation, we ought never to lose sight of a doctor's misconduct. The public expects nothing less, and would look askance at the apparent ease and speed with which some doctors are able to re-apply for admission to the medical register. The GMC must respond to this.

Some will argue that clinical governance and proposals for revalidation will all but eliminate the risk of another Dr Shipman. Of course, they are designed to expose poor practice rather than murderous intent, and so should sound alarms at a rather lower threshold. But in theory a multitude of safeguards already existed in the system which so failed Dr Shipman's patients. All new measures will eventually become pieces of the professional furniture, taken for granted. The risk is ever present that monitoring will become ritualised, a matter of ticking boxes. Circumventing that end result will be the real test for clinical governance.