Hugh Ross exudes brisk efficiency and steely intelligence. He makes you want to think sharper, sit up straighter.He looks as if he would be very good in a crisis.Which he is.

As the chief executive of United Bristol Healthcare trust since October 1995, Mr Ross has weathered arguably the greatest scandal ever to hit the NHS.

The deaths of 29 babies and toddlers following complex heart surgery at Bristol Royal Infirmary in the 1980s and early 1990s is the NHS tragedy that is not forgotten and will not go away.

The story was breaking when Mr Ross joined the trust; to some extent he knew what he was letting himself in for. Yet the cliché about 'poisoned chalices' seems not to apply. 'The reason I was attracted to the job was because Bristol was a very big combined acute trust. I thought it would be a very exciting and interesting career move, ' says Mr Ross coolly.

He is being disingenuous.

Running UBHT (one of the largest trusts in the country with a staff of over 6,000 and an annual turnover of around£200m) even in the best of times would be a challenge. But Mr Ross's half decade at Bristol has been dominated by the need to ensure nothing like the paediatric cardiac surgery debacle can ever be repeated. The task he set was to turn a byword for surgical incompetence into a centre of excellence - not only beyond reproach, but seen to be beyond reproach.

The trust's paediatric surgery mortality rates are now better than the national average. But this success is only the most obvious result of the fundamental reforms. 'We are seen now as one of the leading trusts in the clinical risk field, and clinical governance, and clinical audit. That is been really gratifying.

But There is so much more to do.

This remains one of the biggest trusts in the country, and It is a major teaching trust. It the sort of place that should be among the leaders, 'Mr Ross says.

He insists his task was to 'build upon' good elements, rather than sweep everything away; he claims staff morale in many departments was unaffected by the crisis in paediatric cardiac surgery. And just before he arrived, 'a number of important steps' were taken: the cardiac paediatric surgery had moved to the new children's hospital, the two disgraced surgeons had stopped operating on children, and a new surgeon had been appointed.

'What I needed to do was make sure that audit was robust. Based on my experience, it wasn't as well developed as it should have been.

It was more exclusively doctorfocused than in other places.'

His says his predecessor, Dr Roylance, believed doctors should have the 'paramount' position in clinical audit and expected managers to be 'circumspect' about getting involved. Doctors were handed a great deal of freedom, but were not given the skills they needed to use it effectively.

He says: 'When I arrived clinical directors had no job descriptions, and no formal training [in management and audit]. John [Roylance] assumed that because they were doctors, they would instinctively know how to manage.'

Mr Ross lost no time in introducing new formal audit arrangements, which placed doctors and managers in an equal partnership.

The inadequacy of clinical audit turned out to be part of a wider problem in the organisation, which for years had been dominated by Dr Roylance's personality.

'Some managers had not felt able to be as open as they would have liked; they told me that some things were very wrong.

'People were moved very quickly between jobs, almost at a weekend's notice. There didn't seem to be any objective way to evaluate performance; some people were deemed 'in' and some were deemed 'out'.

I had to make it clear that we were not working on [that] basis.We are a corporate team of managers.'

Ian Barrington, the trust's general manager of children's services since 1992, is an enthusiastic supporter of the new era. Though he did not think to question how things were run before 1995 - 'John Roylance was a very powerful individual and you were not to question the culture' - he now sees the price paid for the freedoms allowed under the 'federalist' system. Directorates functioned like 'mini-organisations', and were ill-equipped to detect problems in themselves, never mind in other areas.

Mr Barrington says he always knew that paediatricians thought the adult cardiac unit was 'not the best place for children to be', but until the scandal appeared on the Channel 4 Dispatches programme, he had no idea what was going on.

'People say: 'How can you not have known? You must have known.' But we were like a lot of small organisations...There wasn't the infrastructure that should have developed.'

Mr Ross's impact has been 'enormous', not just in reform and strategic direction, but in supporting staff through the crisis.

'We are lucky to have him. To be part of a trust going through a public inquiry where no stone is left unturned - you really do require top-level leadership - and he has provided that. He has steered us through admirably.'

Mr Ross has handled the unrelenting media attention by being open, direct - and contrite.

It is the bereaved families, not the press, who made him feel the pressure: 'I have spent many hours with some parents and It is been quite a humbling experience for me. Personally, It is been extremely demanding - this is quite the most difficult job I've ever done.'

In the vanguard: the career of Hugh Ross 1976: joined NHS as graduate trainee, working in Wessex region.Then held a series of posts in London.

1986: unit general manager of the City Unit in Coventry.This unit was a pioneer of waiting-list initiatives in the late 1980s, undertaking work for a number of health authorities in the West Midlands.

1990: unit general manager of Leicester General Hospital, becoming its first chief executive when it was granted trust status in 1992.The hospital was one of the pioneers of Trent region's SIGMA quality programme.

1995: chief executive of United Bristol Healthcare trust.He is also a member of the 31-strong NHS Modernisation Board established to help drive forward the NHS plan.