A HOME Office pathologist, accused of providing misleading evidence that wrongly convicted a mother of murdering her two babies, appeared before the General Medical Council, this week.

Dr Alan Williams wrongly claimed that solicitor Sally Clark - the daughter of former Salisbury police chief Frank Lockyer - had killed her eight-week-old son, Harry, when medical tests showed he had suffered a bacterial infection.

Dr Williams, a forensic pathologist, allegedly misled jurors during Mrs Clark's trial, by initially saying that Harry had died from being shaken, and then changed his finding to smothering.

Mrs Clark, a corporate lawyer, was jailed for life in November 1999 at Chester Crown Court for the murders of her sons, Christopher, aged 11 weeks, in December 1996, and Harry, in 1998.

The 40-year-old served nearly four years of a double life sentence, before the convictions were quashed and she was freed by the Court of Appeal in 2003.

At her trial, damning evidence came from Dr Williams, who made post mortem examinations of both children.

It was claimed she had smothered baby Christopher at the family's home in Wilmslow, Cheshire, and either did the same to Harry or shook him to death.

But at her appeal, it was revealed that samples taken from Harry's body showed he had died from a bacterial infection that had spread to his spinal cord.

It is alleged that Dr Williams had known about the contents of the report since February 1998, but did not disclose the vital evidence to the defence or jury that convicted Mrs Clark.

Dr Williams allegedly did not put the test results on the dead baby's notes and, in his post mortem report, he said there was no evidence of infection or meningitis in Harry's body.

The case against Dr Williams has been brought to the GMC by Martin Bell, a former BBC journalist and independent MP for Tatton, Cheshire, who has campaigned on Mrs Clark's behalf.

Dr Williams, of Macclesfield, Cheshire, could be struck off the medical register if he is found guilty of serious professional misconduct - a charge he denies. It is claimed that Dr Williams, as an expert witness for the Crown, contradicted his opinion of a post mortem examination, failed to give an adequate cause of death and failed to discharge the duties of a competent pathologist.

It is alleged that, during a second post mortem, he did examinations he was not competent to perform, and he failed to provide comprehensive expert evidence in advance for a trial.

The allegations also claim that, for both post mortem examinations, Dr Williams's consideration and treatment was such that it impaired the reliable evaluation of the evidence of cause of death.

It also claimed Dr Williams failed to discharge his duty as an expert witness.

Roger Henderson QC, representing the complainant, said: "This case is not going to permit anybody, neither the committee or the public, to be able to decide why it was that Christopher Clark or Harry Clark died.

"The evidence is going to focus upon the work, conduct, acts and omissions of Dr Williams. It will necessarily be an incomplete presentation of what occurred relating to the deaths of these two boys."

Dr Williams, who denies all the allegations, has given evidence in numerous murder trials, including the killing of James Bulger, the toddler whose body was found on a railway in Merseyside in 1993.

Mrs Clark attended South Wilts Grammar School, Salisbury, before going to Southampton University in 1982.

Her father, Frank Lockyer, a former chief superintendent with Wiltshire Police, and her husband, solicitor Stephen Clark, campaigned tirelessly for her release after she was jailed.

The GMC hearing continues.