A predatory paedophile who was jailed for molesting a boy in a church toilet has been detained indefinitely under a hospital order after he breached a sexual offences prevention order by downloading indecent images of children.

Allan Martin's lawyer had submitted that such an order was draconian and "a sledgehammer to crack a nut".

But two psychiatrists told Maidstone Crown Court they believed the 24-year-old pervert, who has Asperger's syndrome and autism, was a danger to boys and posed a very high risk of re-offending.

Making the order under the Mental Health Act, Judge Charles Macdonald told Martin: "You are going to hospital. You are going to be treated. It will be better than being in prison. Do not fear it. Good luck."

Martin, previously of Woolley Road, Tunbridge Wells, was locked up indefinitely for public protection in February 2011, with a two-year minimum, for sexual assault, attempted sexual assault and breaching his sexual offences prevention order (SOPO).

The sentence was overturned on appeal and a determinate term of two-and-a-half years was substituted, with release at the halfway stage.

Appeal Court judges ruled the open-ended sentence might have seemed an "attractive option" to protect the public, but it was "not available" to now-retired Judge Andrew Patience QC.

Martin was at a talent contest at a Maidstone church when he offended again and breached the terms of a SOPO imposed after committing two other sexual offences.

He molested one boy and tried to assault another. He later declared: "Sometimes I want to go out and really hurt someone. I feel like going out and grabbing someone off the street and hurting them in a way I know is wrong."

Judge Patience described Martin's fantasies as "evil".

In the latest case, Martin was caught with four indecent images at the lowest level of one, downloaded on a Nintendo games console.

Judge Macdonald said he was satisfied Martin had mental disorders and a "sexual preference disorder of paedophilia".

"This is not a case where any custodial sentence would be beneficial to him or provide protection to the public as that of a hospital order," he said.

Martin, he added, had a close interest in male underwear and a preoccupation with offending in public toilets. He fantasised about killing young victims.