"For pioneers in medicine there is a fine line between bravery and recklessness."

That remark, by a senior figure in the medical establishment, sums up the dangers for doctors such as Professor David Southall, struggling to extend the boundaries of medical knowledge. To his admirers, who include some of the most eminent names in the profession, he is a brave man who has walked where few paediatricians dare to go.

To his detractors, his determination to push projects through, and his open espousal of the view that the end justifies the means, has induced a certain recklessness. "Once he gets on the road he goes straight up without pausing at the junctions," one observer said.

Professor Southall arrived at North Staffordshire Hospital from the Royal Brompton Hospital in London in the early Nineties (for a brief period he was working in both locations). His supporters cite a landmark study of cot death conducted at the Royal Brompton in the Eighties in which he demonstrated that a condition known as apnoea, the tendency of babies to stop breathing for short periods, which had been suspected as a cause of cot death, played no role in the condition.

He is also widely regarded as a kind man who was keen on making hospitals friendlier for children. He drew up a child-friendly hospital charter in the early Nineties geared to minimising trauma and pain for children and was always on the look-out for non-invasive techniques. That is what attracted him to the CNEP ventilator - it was gentler, avoiding the rigid plastic pipe forced down into the lungs.

His critics, however, say his readiness to court controversy and to press research to its ethical limit has been demonstrated twice - in his use of covert video surveillance to detect child abuse and in a study in which infants were deprived of oxygen to test a theory that long-distance air travel could be linked with cot death. His use of surveillance to identify cases of Munchausen's by proxy, where parents injure their children to attract medical attention, infuriated some parents who said they were falsely accused. A campaign group published threats and abuse on a website.

Professor Southall has since said that one of his fears is that as a result of the inquiries into his work and his suspension, children will be left at risk of abuse.