Sally Clark, the British solicitor convicted three years ago of murdering two of her babies, was freed last week by the Court of Appeal.

Mrs Clark, who had already lost one appeal, had her case referred back to the appeal court after her defence team discovered microbiology results obtained by Alan Williams, the Home Office pathologist who carried out the postmortem examination on her second son, Harry. The findings had not been disclosed to police, prosecutors, defence lawyers, or the other doctors in the case.

She was charged with murder after Harry died aged 8 weeks in January 1998, in circumstances which were strikingly similar to …