Vital evidence not given to jury that convicted Sally Clark of killing sons

The jury that convicted Sally Clark of murdering her two sons was not told crucial medical evidence that could explain one of the deaths, it emerged yesterday.

The former solicitor's eight week old boy, Harry, died five hours after being injected with a combined vaccine believed to have potentially life threatening reactions in some babies.

But medical experts who testified at her trial, including discredited paediatrician Professor Sir Roy Meadow, assured jurors they could discount any possibility that immunisation was a cause of death.

Mrs Clark, a solicitor from Wilmslow, Cheshire, was found guilty in 1999 of smothering Harry and her first child, 12-week- old Christopher, after the Professor told the court that he could not think of any natural explanation for their deaths.

She was finally freed four years later after a huge campaign by friends, family and other supporters who recognised a gross miscarriage of justice.

The jury at her trial did hear that Harry had received the three in one DTP inoculation against diphtheria, tetanus and pertussis (whooping cough) that is routinely given to babies at two months.

But it was not told that the jab's pertussis component has been implicated as a cause of permanent brain damage and death.

Details of the risk had been outlined in an unpublished 150-page report to the Department of Health by Dr Gordon Stewart, emeritus professor of public health at the University of Glasgow and a world authority on vaccine safety, the Spectator magazine reported.

Professor Stewart's first study was submitted at the request of the chief scientist in 1983, 15 years before Harry's death.

The vaccine also contained the mercury-based preservative thiomersal, which has now been phased out in this country following claims that it may have contributed to a rise in developmental disorders, especially autism.

Harry's breathing, which was being monitored following the sudden death of his Mrs Clark's first son, showed he was unusually dozy from the time he was vaccinated until his death a few hours later.

But despite this, the defence opted not to put the theory that Harry may have died because of an adverse reaction to the jab to the jury.

Medical uncertainty over the potential risks of the DTP injection and fears that airing them in a high profile court case could undermine public confidence in the vaccine meant that even paediatricians testifying on Mrs Clark's behalf told the defence that they would dispute the theory if asked about it in the trial.

The jury did, however, hear Professor Meadow's grossly misleading claim that the odds against two cot deaths happening in the same family were 73million to one. The true figure is around 200-1.

Mrs Clark was duly convicted, and in October 1999 she was given two life sentences at Chester Crown Court.

The case became a cause celebre and the convictions were eventually quashed in January 2003.

But she never got over her wrongful conviction and died from a suspected heart attack in March, aged 42, while her devoted husband Steve was away on business.

Angela Cannings and Donna Anthony were also jailed for killing two children largely on the evidence of Professor Meadow and his now-infamous "law" that "one sudden infant death is a tragedy, two is suspicious and three is murder, unless proven otherwise". Both women were freed on appeal.

In 2005 Professor Meadow was struck off by the General Medical Council for giving "erroneous" and "misleading" evidence.

He was later reinstated, after an appeal to the High Court where a judge ruled he had acted in good faith.