An arsonist who torched a £200,000 barge and started several other fires out of the county has been detained indefinitely under a hospital order.

Ryan Roberts was said to still be in denial and had threatened to burn down a hospital where he was being treated and climbed onto the roof and hurled slates.

Then aged 19, he set fire to the 1920s 40ft Dutch cargo boat Anna Maria belonging to Christopher Barnes at Acorn shipyard in Rochester.

The other fires started deliberately were at St Bedes School in Eastbourne, East Sussex, wooden steps at the cliff top of Beachy Head and a beach cafe in Winchelsea.

He was charged with four offences of arson and five of damaging property.

Roberts, formerly of Rochester, was not present at Maidstone Crown Court having been found unfit to plead. A jury decided that he “did the act”.

The barge blaze destroyed the interior at the shipyard in Gas House Road on November 13 2016.

At St Bedes School, Roberts damaged the dining room, kitchen and serving counter, and five mini buses on October 17.

The fire at Beachy Head was on December 10 2016 and at Winchelsea Beach Cafe, owned by Shaun and Sam Cratchley, on March 28 last year.

Prosecutor Patrick Dennis said Roberts, now 20, was always in the vicinity when the fires broke out.

“He doesn’t like people, he doesn’t like dogs, he is a loner,” he told jurors. “He clearly isn’t well.”

Mr Patrick said it was clearly Roberts on CCTV footage at 7.40am before the barge caught fire.

“There he is, he same slow ambling walk,” he said. “Walking slowly to where the barge is about to be set on fire.”

Daniel Benjamin, defending, submitted that the hospital order under the Mental Health Act should not be without limit of time.

But Judge David Griffith-Jones QC agreed with two psychiatrists that the restriction should apply to Roberts, who moved from Medway to Wembdon in Bridgewater, Somerset.

The court heard Roberts, who suffers from a mental disorder, did not like being at a hospital in Hook, Hamshire, in June last year and threatened to burn it down. He was said to be adamant he did not set the fires.

“The medical evidence suggests he poses a risk of causing physical injury to others,” said the judge. “He remains in total denial in the face of absolutely compelling evidence.

“I make it clear I have no hesitation in agreeing such an order is demanded. It seems to me serious harm to the public is not confined to physical injury. Significant damage to property will suffice for such purposes.

“Evidence of his behaviour in hospital shows that subject to stress and anxiety he is liable to act erratically. He has a history of committing arson.”

The judge said in making the “draconian” order, he did not ignore the fact that Roberts had begun to show signs of improvement.

“That is encouraging,” he added. “I very much hope that improvement will be sustained and, indeed, increase. It is, however, plain he has some way to go.

“He remains in total denial, and that is currently inhibiting any work the treatment team are no doubt anxious to institute.

“I very much hope the time will come where it will be possible for him to revert to life in the community.”

Roberts will be detained at a medium secure hospital in Diss, Northfolk, until it is considered safe for his release.