The principal abuser, Jeffrey Tanner, 54, was cruel and depraved, the judge at King's Lynn Crown Court said.

Tanner and his wife Brenda Tanner, 53, of Gladstone Street, Peterborough, Cambridgeshire, were found guilty of abuse and cruelty to three people who had lived with them, two of them children.

Tanner forced a boy in his care to drink urine and eat faeces as a punishment.

You have been convicted of offences of cruelty, offences of depravity, offences of the breach of the greatest trust

Judge Isobel Plumstead

Another victim told police that she had been made to dance naked while holding heavy weights above her head.

One of their victims was a girl placed in their care by Cambridgeshire County Council who employed them as foster carers in the 1980s.

They were also unofficial foster parents to their second victim - a boy - with social workers' knowledge, the court was told.

The third victim, a woman now 40, was an adult who stayed with the family after becoming homeless.

All three had special educational needs and had endured difficult upbringings, the court heard.

The Tanners were convicted in April following a month-long trial. For legal reasons the outcome of the trial could not be reported until now.

Unlawful wounding

Jeffrey Tanner was convicted of cruelty, administering noxious substances, unlawful wounding, assault and putting one of his victims in fear of violence.

He was cleared of indecency with the girl.

Brenda Tanner was convicted of cruelty to the two children and grievously harming the boy.

She was cleared of indecently assaulting the boy and of putting the woman in fear of violence.

Both have been remanded in custody pending sentence next month.

Judge Isobel Plumstead said the Tanners had been guilty of a breach of trust and exploitation.

There was no option for Jeffrey Tanner but a very substantial prison sentence.

"You have been convicted of offences of cruelty, offences of depravity, offences of the breach of the greatest trust that anyone could have been guilty of - that is when young people, children, are entrusted to their care.

"That these two young people had been very cruelly and harshly neglected and ill treated by others by others does not make it any better.

Serious harm

"In fact, in a way, it makes it worse, because each of these children were put into your household so they could get away from the squalor and filth that they had seen before."

The judge told Brenda Tanner: "Mr Tanner was the driving force but no adult who assumes care of a child can be regarded as less than responsible for that child if that child is neglected or abused in that household.

"The jury has found you guilty of inflicting serious harm. A custodial sentence is an inevitable consequence."

The couple hugged and wept in the dock before being taken away.