Dr Bolsin, 45, is now practising medicine in Australia - he claims he was virtually driven out of the UK after blowing the whistle on surgeons at Bristol.

One of the most memorable images from the original General Medical Council hearing into the Bristol affair was the sight of Dr Bolsin in tears in the witness box as he described an eight-year battle to bring the scandal to light.

He told the hearing: "In the end I just couldn't go on putting those children to sleep, with their parents present in the anaesthetic room, knowing that it was almost certain to be the last time they would see their sons or daughters alive."

In the end I just couldn't go on putting those children to sleep

Dr Stephen Bolsin

But other evidence given by some doctors to the GMC makes it clear that some closely connected to Bristol still think his intervention, or at least the manner in which he chose to release his figures, had a foundation in internal political maneouvring.

In fact, the Bristol Inquiry has heard how Dr James Wisheart, the surgeon at the heart of the scandal, and Dr John Roylance, the trust's chief executive, had actually contemplated sacking Dr Bolsin after he carried out his own survey on the surgeons' death rates.

Concerns were legitimate

An accurate picture of the tensions surrounding paediatric cardiac surgery may not emerge even after his marathon four-day stint at the inquiry, but what has been proved is the legitimacy of his concerns.

The so called 'Bolsin audit', although compiled from far from perfect raw materials, revealed desperately poor results in key areas of surgery at Bristol - and those figures have been borne out by a more thorough analysis by inquiry-appointed experts.

The picture painted of Dr Bolsin is one of a fairly inexperienced doctor in opposition to senior and powerful figures.

Dr Bolsin says he was ignored by senior staff

In fact, by the time he began secretly compiling mortality figures using data from various sources, he was already an experienced statistician.

He joined the Bristol Royal Infirmary in 1988 from another specialised unit at Great Ormond Street Hospital in London, and immediately noticed that operations to correct congenital heart defects in babies were taking much longer than they should.

These delays have now been highlighted as potentially critical in at least some of the deaths examined by the inquiry experts.

'Ignored by management'

He says he attempted to use the results of the audit internally to draw the attention of management to the problem, but with little response.

"I was told specifically to keep the train moving, and not to pull the communication cord."

It was through the columns of Private Eye's MD, Dr Phil Hammond - who presents the BBC's "Trust Me I'm a Doctor" - that the figures were first made public.

Dr Hammond has conceded that Bolsin was a key contact in writing his stories, which described Bristol as "The Killing Fields" - even though the anaesthetist denied at the GMC to having been the source.

After the scandal broke in 1995, Dr Bolsin continued his NHS practice, but said he felt ostracised by the medical establishment, and was passed over for lucrative private work.

Dr Bolsin and his wife Maggie, who also worked at Bristol Royal Infirmary, left for Geelong Hospital near Melbourne shortly afterwards.

But although he says his life in Australia is good, he would still like to return to the UK.

However he says the system of 'patronage' in the British medical profession, which turned against him after Bristol, has probably made him 'unemployable'.