A young sex offender who has repeatedly vowed to take revenge on his victims has been detained indefinitely under the Mental Health Act.

Michael Stone committed offences with pervert pensioner Donald Down, 76, of Winchester Crescent, Gravesend, who was jailed earlier this month for eight-and-a-half years.

Stone, 20, of Valley Drive, Gravesend, was found to be unfit to plead to offences of attempted rape, causing a child to engage in sexual activity, sexual assault and sexual activity with a child.

A jury had to decide whether he “did the acts” and concluded he was responsible for one offence of sexual assault, involving touching, and one of inciting a child to engage in sexual activity, involving persuading a boy to get into a bath with him.

Consultant psychiatrist Dr David Thomas told Maidstone Crown Court Stone suffered from a mental disorder and needed treatment programmes to reduce the risk of committing more offences.

“He doesn’t have the internal resources to modify his behaviour,” he said.

“A lot of what he does is bravado, but we have had repeated assertions by him to abscond and exact revenge on those he believes are responsible for his incarceration.

“I do believe if he had the opportunity, he would return to the area and seek to establish contact with the victims and their families. What happens then is anybody’s guess.

“I suspect some of it is bravado and machismo but given the chance he would act as he says.”

Dr Thomas said Stone’s response to treatment was probably going to be “modest”, adding: “It could take 18-24 months given his intractable position of total denial.”

Judge Michael Carroll said he was bound to make a hospital order. “I don’t have a choice,” he continued. “He is not suitable for treatment in the community.

“There was an element of taking hold of these boys and taking them to the address and an incident with a fishing needle.”

The judge said of the threats: “I appreciate it is bravado but it is still frightening to hear it.”

He added: “I am satisfied a hospital order should be made. He should not be released without careful consideration, either by the Secretary of State or the mental health tribunal.

“This is about managing the risk of serious harm to members of the public. I must make a restriction order without limit of time.”