A paedophile who preyed on vulnerable children in care homes was jailed for four more years after two more victims came forward.

Gordon Knott was originally sentenced to 16 years imprisonment in 1997 after he was convicted of ten sex crimes against eight boys and a girl in Edinburgh children's homes in the 1970s and 1980s.

But after a decade of freedom following his release in 2008 he was imprisoned again after two further victims spoke to police about the abuse they suffered from him while in care.

The men testified at a new trial at the High Court in Edinburgh that they had also been targeted by Knott, who was one of the first male house parents to be employed in Edinburgh children's homes to look after disadvantaged and vulnerable children.

Both said that as children in the local authority care system they were made to carry out sex acts on the man employed to look after them.

A jury earlier found Knott, 64, guilty of three charges of indecency against the two victims committed in Clerwood, at Arthur's Seat and at an address in the Liberton area between 1973 and 1981.

A judge told Knott on Tuesday: "You have been convicted by the jury of the repeated, calculated and predatory sexual abuse of two young boys while you were responsible for their care in children's homes."

Lady Scott pointed out that the former house father had terrified victims and that rather than protecting them he had abused them.

The judge said that she took into account that he had not re-offended since his release from the earlier sentence and had been of good behaviour, but rejected a defence submission to spare him a prison term.

The abuse of one boy began when he was aged five.

He told the court that on one occasion Knott had taken him to Arthur's Seat on the back of his motorbike and after parking him took him up the hill, where Knott carried out the abuse.

He added: "If I had a gun I would have shot him. I would have done anything to get away from him."

He added: "I was crying at the same time but it didn't stop him."

He said that afterwards his abuser drove him back to a care home and added: "As far as I can recall I went straight up to my bedroom crying my eyes out."

The man, now 49, said that Knott appeared to always be nice to everyone but said: "He just seemed like a really nice person at the time if you didn't know him deep down."

The second victim, also 49, was also abused from about the age of five and said he left care as a teenager.

He said he was too scared to tell anyone about what was going on and was told that if it was found out he would be split up from siblings who were also in care.

He said that as he grew older he tried to put it all behind him and "blacked it out" but as his first child grew older it brought back a lot of memories.

"I though maybe I needed to say something so I phoned the police," he said.

Knott, of Carstairs Road, Carstairs, in Lanarkshire, had denied the latest charges to be brought against him following the two victims making contact with police, but was earlier found guilty of the offences.

Defence solicitor advocate Brian Gilfedder said Knott had acted as a carer following his release from his previous jail sentence and added that a report prepared on him highlighted he could be managed in the community.

Knott was placed on the sex offenders' register for life.