Stephen McNally, 44, a driver with Strathclyde Regional Council’s social work department, sat motionless in the dock as the jury returned its verdict.

Lord MacLean told McNally that he was sentencing him to the maximum

term allowed on one of the charges involving a 12-year-old girl.

The girl was one of 27 children cared for by McNally and his wife at their homes in Oban and Connel, Argyll.

The three other charges involved girls who were not in the care of the couple, the court heard.

Lord MacLean told McNally that the most serious offence involved the 12-year-old, because she had been placed in his care as a foster father and trusted by her and society.

The offences came to light after a 22-year-old woman walked into

Lochgilphead police station and reported that she had been abused by McNally 10 years earlier, while he was baby sitting in her home in Oban.

She told the High Court in Glasgow that she could not sleep at night because she was worried that other children in McNally’s care might have been abused by him.

He was originally also charged with raping the 12-year-old girl who had complained to her new foster mother about what had happened.

However, as there was no medical evidence produced in court, the Crown dropped the charges.

The girl told how McNally abused her repeatedly at night. The court heard how he had made an application to foster the girl, but the allegations came to light before the application had been granted.

His wife, Mrs Trudy McNally, 42, a member of the child help link, ChildLine, the children’s hearing system, and a registered child minder, was helped from the court, distraught and unable to speak.

Earlier she had told the jury how her life had become a ”horror situation” after the allegations had been made against her husband.

McNally was also found guilty of indecently assaulting a girl several years ago, when she was five years old.

The court also heard how another girl, who was then 14, escaped McNally’s attentions when she objected strongly as he kissed her during a mock fight he had instigated.

When asked in the witness box why four different girls would make such allegations against him, McNally said he did not know and accused them of lying.

McNally was vetted by Strathclyde region’s social work department before being given the position of trust. After the court case a senior social worker said that, unless an applicant had a criminal record, it was almost impossible to detect potential abusers.

Defence-advocate Graham Robertson told Lord MacLean that there was little he could say on behalf of McNally, except that his life was now in ruins.

McNally was convicted on five charges against four of the girls. Two of the charges related to the 12-year-old.