Margaret Smith, 39, collapsed in the dock at Newcastle Crown Court after the jury found her not guilty of smothering her son, Keith, at their home in Hull in September 1994.

Professor Meadows, once regarded as the country’s leading expert in the field, played a “significant” part in the mother-of-nine’s conviction in 2002.

Mrs Smith’s ordeal will lend further weight to the case against the Professor, who faces a hearing over charges of serious professional misconduct before the General Medical Council in January for his role in the cases of Trupti Patel, Angela Cannings and Sally Clark.

A review of 297 prosecutions for child murder, manslaughter or infanticide has led to letters being sent to lawyers in 28 cases, suggesting that the conviction be considered by the Court of Appeal or the Criminal Cases Review Commission.

In yesterday’s case the jury was not told that Mrs Smith had been convicted of murdering Keith, but cleared of killing her 5½-month-old daughter, Kelly, who died in 1992. Nor was it told that Mrs Smith and her second husband, Keith Smith, were jailed for stabbing her first husband to death in 1995. Robert Brannan, 53, was discovered in his bath with 51 stab wounds.

Mrs Smith was charged with murdering baby Keith after a girl came forward to say that she had witnessed her killing the child by placing a pillow over his face until his legs stopped kicking and he stopped crying.

Professor Meadows told the jury in the original trial to be suspicious that Mrs Smith had taken Keith to hospital complaining that he had breathing difficulties, although doctors found nothing wrong with him. He said that this was common in cases where women later kill their children. He told the jury: “One cot death in a family is rare and two is even rarer.”

Mrs Smith’s lawyers later argued against her life sentence before the Court of Appeal. Gary Burrell, QC, described the original trial as “flawed” and Professor Meadows’ contribution as “prejudicial”.

He said that the child expert had made it easier for jurors to believe the girl’s claims. During the retrial the defence questioned the claims of the girl, who was aged 7 when she claimed that she saw Mrs Smith smothering her baby. The jury was told that there were inconsistencies in her account. She had said that she was away from school on the day Keith died, but a school register was provided showing she was present.

Mrs Smith did not give evidence at the retrial. The post-mortem examination showed that cot death was the most likely cause of death. The court heard that Mrs Smith’s home was filthy, smoky and had few carpets. She did not appear to have the normal affection of a mother for her child. Mr Burrell, for the defence, said that although his client was an inadequate mother, it did not make her guilty of murder.

The verdict follows successful appeals by Angela Cannings and Sally Clark, as well as the acquittal of pharmacist Trupti Patel, who were all accused of murdering their babies.

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