Damian Green, a Tory frontbench spokesman who is part of the cross-party group, believes the guidelines are encouraging social workers and schools to be overzealous in their attempts to find MSBP. He said: “You have the possibility of huge injustices arising through the inflexibility of these guidelines which are based on questionable theories.”

Other members of the group include Earl Howe, a shadow health minister; Jon Cruddas, the Labour MP for Dagenham; Dr Richard Taylor, a retired consultant and independent MP for Wyre Forest; Nick Gibb, MP for Bognor Regis and Littlehampton; and Lynne Featherstone, the Lib Dem member for Hornsey and Wood Green.

The MPs are concerned by huge geographical variations in the number of families being placed under investigation by social workers. In 2003, 264,000 parents or children faced “initial assessments” by social workers who suspected possible abuse.

While in Buckinghamshire there were only 540 initial assessments, in Kent the number was 12,510. Even allowing for differences in their populations, parents in Kent were 10 times more likely to be investigated over child protection issues. The report argues this discrepancy may be explained by some areas disregarding the MSBP hypothesis, “whereas in others it is taken as gospel and applied with zeal”.

The report has brought to light a number of harrowing cases. They include that of Tina England, one of Gibb’s constituents, who had both her adopted children placed on an “at risk” register because West Sussex social services thought she had MSBP. Her elder son Donald (not his real name), now 20, who has cerebral palsy and learning difficulties, was experiencing stomach pains and England was advised by medics to put him on a special diet.

()But social workers became concerned that she was exaggerating his disabilities and showing signs of MSBP. They considered both Donald and his 14-year-old brother Nigel (not his real name), who has more severe learning difficulties, as well as autism and epilepsy, to be at risk.