The former Labour MP who exposed the miscarriage of justice over the Birmingham Six has drawn parallels with the conviction of nurse Lucy Letby – saying the case against her has ‘not been proven beyond reasonable doubt’.

Chris Mullin led the campaign through ITV‘s World in Action to prove that the men jailed for the Birmingham pub bombings had been falsely convicted in what has been described as ‘one of the greatest feats ever achieved by an investigative journalist’.

Mr Mullin, who went on to become MP for Sunderland South and a minister in Tony Blair‘s Government, dismantled the evidence of the main prosecution witness, Dr Frank Skuse, a Home Office forensic scientist who told the court that there was a 99 per cent chance that at least two of the accused had recently handled explosives – a claim that was later totally discredited.

Mr Mullin says that Letby’s increasingly controversial conviction also depended on the evidence of one expert witness – in her case, Dr Dewi Evans, whose evidence in court about the causes of the deaths of 17 infants at the Countess of Chester Hospital was heavily questioned at a press conference earlier this month.

Professor Shoo Lee, a neonatologist whose academic work was cited by the prosecution during her trial – incorrectly, he says – convened an international panel of medical experts who concluded that Letby had not murdered or attempted to murder any babies.

Last night, Mr Mullin told The Mail on Sunday: ‘I cannot, hand on heart, say that Lucy Letby is innocent, only that the case against her was not proven beyond reasonable doubt.

‘The one thing that her case has in common with that of the Birmingham Six is that it is heavily dependent on the evidence of an expert witness.’

Questions about Dr Evans, a retired consultant paediatrician, were raised during Letby’s trial.

Chris Mullin (pictured) led the campaign through ITV ‘s World in Action to prove that the men jailed for the Birmingham pub bombings had been falsely convicted

The former Labour MP who exposed the miscarriage of justice over the Birmingham Six has drawn parallels with the conviction of nurse Lucy Letby (pictured)

In an unusual move, Appeal Court judge Lord Justice Jackson wrote to the trial judge, Mr Justice Goss, telling how a report Dr Evans drew up in an unrelated case had been dismissed as ‘worthless’ and claimed Dr Evans had breached his duty as an expert by deciding on the outcome he wanted and then ‘working out an explanation’ to achieve it.

Last week The Economist magazine joined the growing chorus of those raising doubts about Letby’s conviction, saying: ‘The case has not only revealed horrors in the way hospitals care for babies.

‘It has exposed deep flaws in the criminal justice system, and risks further undermining faith in the law.’

The influential magazine quoted Professor Jane Hutton, a medical statistician at the University of Warwick, who was ignored when she warned the police investigating the baby deaths that their attempt to build a case against Letby on the basis of her work shifts was flawed.

She said: ‘I think it’s beyond reasonable doubt that this conviction is not safe. Not only that, in my opinion, it’s beyond reasonable doubt that there should never have been a trial.’

Dr Evans stands by his evidence.

The Birmingham Six were six men from Northern Ireland who were each sentenced to life imprisonment in 1975 over the 1974 Birmingham pub bombings.

Their convictions were quashed by the Court of Appeal in 1991 and the six were each awarded compensation ranging from £840,000 to £1.2 million.