Sally Clark was also convicted on evidence from Sir Roy Meadow

Sir Roy was a prosecution witness during the original trial, but his evidence was heavily criticised by QC Michael Mansfield during Mrs Cannings's appeal.

Mr Mansfield argued that, were the trial to take place now, it was unlikely the Crown would call Professor Meadow as a witness, or, if they did, it would "have to be done with a health warning attached to it".

Sir Roy Meadow Educated at a grammar school in Wigan and Oxford University Worked as a GP in Banbury Became a senior lecturer at Leeds University Took up chair in paediatrics and child health in 1980 at St James's University Hospital, Leeds Former president of British Paediatric Association Former president of the Royal College of Paediatrics and Child Health Knighted in 1998 for services to child health

Professor Meadow was also a central figure in two previous similar cases.

Solicitor Sally Clark won her appeal in January to overturn her conviction in 1999 for murdering her two baby sons and pharmacist Trupti Patel was found not guilty in June of murdering her three babies.

Giving evidence at the trial of Mrs Clark, Sir Roy told the jury that the chance of two children in such an affluent family dying of cot death was "one in 73 million".

But his claim was disputed by the Royal Statistical Society, which wrote to the Lord Chancellor to say there was "no statistical basis" for the figure.

And Sir Roy's estimate was criticised as "grossly misleading" and "manifestly wrong" by a judge during Mrs Clark's second appeal hearing.

Munchausen's

Sir Roy first came to prominence in 1977 after publishing a paper in The Lancet medical journal on a condition he dubbed as Munchausen Syndrome by Proxy.

This is a form of child abuse in which a parent induces real or apparent symptoms of a disease in a child.

Perhaps the most high profile example was the case of nurse Beverly Allit, who murdered four children and harmed nine others. Professor Meadow worked in this case.

But even his work in this field has been subject to controversy.

In the House of Lords recently, Earl Howe, the Opposition spokesman on health, accused the professor of inventing a 'theory without science' and refusing to produce any real evidence to prove that Munchausen Syndrome by Proxy actually exists.

Meadow's law

However, Sir Roy is most renowned for an observation in a book that became universally known as "Meadow's Law".

This states that: "one sudden infant death is a tragedy, two is suspicious and three is murder, unless proven otherwise."

He has since gained him a reputation for being particularly severe when confronted with cases of multiple child deaths in one family.

Many supporters, however, have championed Professor Meadow, calling him a man of great skill and compassion.

It is also true that the Court of Appeal decision to quash Mrs Clark's murder convictions did not hinge on Professor Meadow's statistics.

Instead, the crucial factor was the revelation that evidence from pathologist Dr Alan Williams had not been made available at the original trial.

A CPS spokeswoman said Professor Meadow did not use statistics in the Patel and Cannings trials and had been just one of a number of expert witnesses to be called by the prosecution.

Asked whether he would be called again as a witness, she said: "There is no professional body that has found against Professor Meadow that we are aware of.

"It would depend on the case and what the evidence was whichever expert was chosen."

The General Medical Council said they were investigating Prof Meadow but would not release any further details.