A handful of mothers and fathers who have had their children taken away took part in a demonstration outside the high court in London to argue for changes to the family court system.

Two recent cases have led to public criticism of the use of medical experts: Trupti Patel was cleared last month of murdering three of her babies, and Sally Clark was cleared on appeal earlier this year of killing her two children.

The evidence of the expert witness Professor Sir Roy Meadow was criticised in both cases.

Sir Roy has given evidence in several cases of the sudden deaths of babies, using the diagnosis of Munchausen's syndrome by proxy to say parents of carers have intentionally harmed or killed their children while claiming it was a natural illness.

Several of the parents in yesterday's protest claimed Sir Roy was involved in their cases and questioned his evidence.

Penny Mellor, who organised the demonstration, called for a "full, immediate public inquiry" into all aspects of child abuse and the family court system, because there was too much secrecy and par ents were "gagged". "We are here to expose the secrecy of the family courts in which Professor Meadow and other experts have given evidence," she said.

Ms Mellor, of Wolverhampton, said she had taken up the cause of parents wrongly accused of child abuse because she was a mother of eight and believed in fighting for what is right.

Also outside the court was Terry Cannings, whose wife Angela, 40, was convicted of murdering two of their children last year. An appeal has been lodged.

Mr Cannings, 49, said he had decided to attend because he could relate to the other parents' stories and wanted a change in the way child abuse cases were handled.

"Every day since she was convicted has been a misery. Angela has lost control of her life and I have lost control of my life. Angela is coping, but I feel she needs something to cling on to. They have ripped the heart out of her."

Last week the attorney general, Lord Goldsmith, announced that he was appointing a group to consider whether an in-depth review was needed of cases involving Alan Williams, a pathologist whose evidence was criticised in Mrs Clark's case.