The boy, now 12, is back in council care and seems unlikely to be able to lead an independent life. The parents argue that if they had known the boy's history, they would not have adopted him. They say their five years of ignorance meant he was denied the correct treatment which might have saved him.
Several of the boy's brothers and sisters have had similar experiences since being taken into care in 1985.
The couple, whose name cannot be published because the identity of the child has to be protected, have been granted legal aid for their case. They allege that based on internal documents and reports they have been shown since, it was known and recorded that the child had been abused, and they were never told.
They are claiming for the material and emotional cost of the years they spent with the boy, although they insist their main concern is to bring their experiences to the attention of other couples and social services departments.
Both Solihull council, which first took the child into care, and Barnardo's, the agency which arranged the adoption, say they cannot comment in detail on individual cases, but deny there was any failure to disclose information.
The case is likely to provide a focus for a debate, among those working in social services and adoption, over the best way to cope with the placement of sexually abused children, or those suspected of having been abused.
In some cases the abuse remains undisclosed for years, only to erupt in later life. Other abused children can be treated like any others, yet never display any symptoms of abuse.
As well as the emotional suffering at stake, large sums of money hang on the right decisions. If placements break down, the cost of keeping a child in an institution is pounds 30,000 a year or more. The only major study of the treatment of abused children suggests that the case which has come to court is far from an isolated example.
Catherine Macaskill, a social work consultant, interviewed 66 substitute families who had fostered or adopted a total of 80 children between 1985 and 1989. In a third of the cases she studied, the families had no prior knowledge of the sexual abuse. In six placements the professionals knew about the abuse, and deliberately concealed it from the family.
She published her findings last year, and concluded: 'Concealing information about sexual abuse from substitute families or providing sparse information achieves nothing positive and merely places the abused child and members of the substitute family in an excessively vulnerable position.
'It is unfair to expect substitute families to engage in this challenging task without adequate preparation and training.'
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