Mrs Clark was found guilty in but was cleared by the Court of Appeal in 2003 after new medical evidence emerged which had not been presented at her trial.

In a statement announcing her death, Clark's family said:

"The matter is in the hands of the coroner and it is too early to provide any further information. Sally, aged 42, was released in 2003 having been wrongfully imprisoned for more than three years, falsely accused of the murder of her two sons. Sadly, she never fully recovered from the effects of this appalling miscarriage of justice."

Clark was found dead on Friday morning.

She and her husband, Stephen, had lived in Wilmslow, Cheshire, but her family moved to Chelmsford to be closer to her while she was in prison in Essex. The family's solicitor, Sue Stapeley, said it would be "unwise to speculate" on the cause of Clark's death.

Clark was convicted after a trial at Chester Crown Court of smothering her 11-weekold son Christopher in December 1996, and eightweek-old Harry in January 1998. She was given two life sentences.

At the trial, Professor Sir Roy Meadow claimed the probability of two natural unexplained cot deaths in an affluent family was 73 million to one. But that figure was disputed by the Royal Statistical Society, and other medical experts who put the odds of a second cot death in a family at 200 to one.

In 2003, the Court of Appeal was told that new medical evidence suggesting that Harry may have had a brain infection was withheld from Clark's defence team during the trial.

Her barrister said at her successful appeal that new evidence emerged in 2000 that Harry had had an infection, and that the prosecution pathologist had known about it since February 1998.

In June 2005, Professor Meadow appeared before the General Medical Council charged with serious professional misconduct in relation to his evidence at Clark's trial.

The GMC found the case proved and struck him off, but both actions were overturned in the High Court in February last year.