Munchausen’s began life in 1951 as a catchphrase for an overanxious mother, phantom-suffering her child’s pain. In 1977 a clever paediatrician, Dr — now Professor Sir Roy — Meadow mutated it to describe two healthy children whose mothers had fabricated their illnesses. It made his name. He thought it rare. It provoked controversy, not least because a mother’s denial was proof of MSbP. Two questions demanded answers: what exactly was it and how prevalent? The Government’s Griffiths inquiry recommended “an expert and multidisciplinary panel to review methods of identification”. A working party with only two doctors on it, neither a paediatrician, focused not on identification, but on how to translate suspicion of it into proof. Confirmation duly came to pass. The guidelines of the working party were validated.

Since then, hundreds have claimed irreparable damage to their families by false allegations of MSbP For years the incidence of violent abuse of children has fallen consistently; by more than 50 per cent since 1996. Yet in response to just one case — the horrifying killing of Victoria Climbié, who was let down by social and medical services — the Government is creating the Children’s Index containing explicit details of every child from every source. Such a pharmacy of intimate information could provide many more MSbP prescriptions with tragic outcomes.

Any of the following may put a mother in the MSbP “frame”: if the doctor can find nothing wrong with the child; if tests are negative; if mum demands other opinions; if she has an “unhealthy” interest in things medical; if she exaggerates the child’s condition; and, of course, if she denies making it all up. For the health service, MSbP is a cheap solution to difficult cases. Some doctors call it a sexy diagnosis.

In Medical Hypotheses, a respected American journal, Dr Virginia Sherr reports many cases of Lyme disease — notoriously difficult to diagnose — treated as MSbP, with, sometimes, fatal consequences for the child. In the BMJ, Charles Pragnell, a former social worker, cites many stigmatised parents refusing to seek treatment for their sick children for fear of child abuse allegations; one doctor diagnosed MSbP 258 times.

The medical establishment justifies MSbP because many mothers have confessed to it. Would any innocent mother say that she had abused her child when she hadn’t? Commonly, a social worker, psychologist or paediatrician will say: “If you deny it you will never see Sandra again; if you admit it, you will keep her and receive treatment for your condition.” Mother and her partner may agonise but the loss of their daughter is unthinkable. So “Sandra’s” mum “confesses”. And that probably guarantees that they will never be a family again. And the “confession” goes into the statistics; another “joker” in the MSbP house of cards.

Accused, a BBC Two documentary, told the shocking story of a mob-handed, dawn raid in the Scottish island of South Ronaldsay, in 1988, when nine terrified children were forcibly torn from their parents on a social services’ fantasy that they had been subjected to ritual satanic abuse. A family court judge quickly rubbished the “prosecution” and sent the children home. The social workers involved are, 17 years later, unrepentant, convinced that the denials — by all the children and their parents — prove the abuse took place. Welcome to the witches’ drowning pool.

What should be done? The Children’s Index should be scrapped. Such a police state measure could multiply miscarriages of justice. Judges should throw out expert evidence based on MSbP, citing the judgment of the Queensland (Australia) Court of Appeal, in 2004, that “it does not form part of a recognised reliable body of medical knowledge”. The medical establishment should tell all doctors that MSbP is not a medical condition. When a doctor or social worker is convinced that a mother is pretending that her child is ill when it is not, she should be charged with child abuse in a court of law. If the evidence warrants it she will be “convicted” and any children considered for a care order. If the evidence is not there, the mother is presumed innocent.

The author is a solicitor and writer. Stolen Innocence, his story of Sally Clark, is published by Ebury Press