Sir Roy, former president of the Royal College of Paediatrics and Child Health, failed in his duty as an expert witness to explain the limited relevance of his findings, a GMC fitness-to-practise panel said yesterday, when he told Mrs Clark's trial the chance of two babies dying of cot death within an affluent family was "one in 73 million".
Sir Roy admitted yesterday that his use of the statistics had been "insensitive''.
Mrs Clark was arrested in 1998 over the deaths of her sons Christopher and Harry, and in November 1999, after Sir Roy had testified against her, she given two life sentences for their murder. But in January 2003, she had her convictions quashed on appeal, with the judges criticising Sir Roy's evidence.
Yesterday, the GMC panel ruled that some of the child expert's testimony was not balanced and was erroneous in parts when he said at a hearing at Chester magistrates' court that the odds against two infant deaths in a family being natural could be likened to "winning the Lottery".
However, perhaps crucially for the professor, the most senior member of the medical establishment ever to appear before the GMC in a disciplinary hearing, the panel ruled that, in giving his evidence at the trial, he did not intend to mislead.
That finding will be taken into account by the GMC in deciding whether Sir Roy's actions amounted to serious professional misconduct. Should he be found guilty, in a judgment expected today or tomorrow, he could be struck off the medical register. The panel will also consider evidence in mitigation from several senior medical figures who said they believed the professor had the best interests of children at heart.
The 72-year-old child abuse expert from Leeds, now retired, forged an international reputation by being the first physician to describe Munchausen's Syndrome by Proxy, a form of abuse in which parents induce illness in their children to gain attention.
But his credibility suffered a series of massive blows with the quashing of three convictions of mothers for child murder, which had depended on his expert opinion. Besides the case of Mrs Clark, he had testified against Donna Anthony, jailed in 1998 for allegedly killing two of her children but freed on appeal this year, and Angela Cannings, convicted of murdering two of her children in 2002, but freed on appeal in 2003.
The charges, which Sir Roy has always denied, were brought against him at the instigation of Mrs Clark's father, Frank Lockyer.
Mr Lockyer said it was wrong to use the word "happy" in relation to the outcome. Mrs Cannings, 42, from Saltash in Cornwall, said she was "both happy and unhappy" and wanted to wait for the end of the case before making a full statement.Reuse content