A public schoolboy is starting a life sentence for attacking two sleeping students and a teacher with hammers at a boarding school.

The 16-year-old was wearing just his boxer shorts and used weapons he had collected to prepare for a zombie apocalypse.

The teenager admitted assaulting the two boys and the housemaster at Blundell’s School in Tiverton, Devon, saying he was not guilty of attempted murder by reason of insanity because of sleepwalking.

But the jury rejected this and found him guilty at Exeter Crown Court of three counts of attempted murder.

A corridor and the top of a staircase
The two students were attacked as they slept in the boarding house at Blundell’s School (Devon and Cornwall Police/PA)

Trial judge Mrs Justice Cutts said experts were unable to say how long the defendant would pose a risk to the public and imposed a sentence of detention for life with a minimum term of 12 years.

“You planned your offences and used hammers you had bought as weapons,” she said.

“You knew full well if you hit the boys multiple times with the hammers they would die.

“You are an intelligent boy and I am satisfied you knew the difference between right and wrong.

“In my view there remains a significant risk that you could behave in this way again. I consider that you pose a high level of danger to the public because of the nature of your offences.”

The youth, who cannot be identified for legal reasons, had armed himself with three claw hammers and waited for the two boys to be asleep before attacking them.

The two pupils were asleep in cabin-style beds in one of the co-ed school’s boarding houses when the defendant climbed up and attacked them shortly before 1am on June 9 last year.

View of Blundell’s School
The teenager admitted assaulting the two boys and the housemaster at Blundell’s School in Tiverton (R-Jay/Alamy/PA)

Housemaster Henry Roffe-Silvester, who was asleep in his own quarters, was woken by noises coming from the boarding house and went to investigate.

When he entered the bedroom where the attack had happened, he saw a silhouetted figure standing in the room, who then turned towards him and repeatedly struck him over the head with a hammer.

Another student heard Mr Roffe-Silvester shouting and swearing as he fled the bedroom and dialled 999 – believing there was an intruder.

The two boys were discovered in their beds a few minutes later.

They had suffered skull fractures and injuries to their ribs, spleen, a punctured lung and internal bleeding.

The court heard both are living with the “long-term consequences” of the attack but have no memory of the incident. One boy suffered permanent brain damage.

Mr Roffe-Silvester received six blows to his head but made a full recovery.

During the trial, James Dawes KC, prosecuting, told jurors: “The investigation has uncovered an obsession that the defendant had with one of the boys, an obsession with hammers as weapons, and an obsession with killing and killers and the killing of children.

“Mr Roffe-Silvester said he thought the defendant appeared to be ‘on a mission’ and afterwards his face and body relaxed.”

But one expert told the jury the boy would have been sleepwalking.

Hammers on floorboards
Hammers discovered at the scene of the attack (Devon and Cornwall Police/PA)

Dr Mark Pressman described the attack on Mr Roffe-Silvester as “a textbook example of sleepwalking violence”.

Another expert, Dr John O’Reilly, said he did not believe the boy was asleep because a sleepwalker does not initiate violence because it is triggered by noise or touch.

Giving evidence, the boy said he kept two hammers by his bed “for protection” from the “zombie apocalypse”.

The boy added: “I feel very terribly sorry for all three individuals because of what I did to them.”

Kerim Fuad KC, defending, described the incident as a “tragic and extraordinary case” and said the boy has since been diagnosed with autism spectrum disorder.

He said the teenager was struggling from a combination of difficulties, including exams, issues in his personal life and an “unhealthy interest in violence and violent films”.

“This was a very unhealthy cocktail of extreme stress,” he added.

Speaking after the sentencing, Detective Inspector Dave Egan said: “The assaults were both brutal and savage and I have no doubt that his intent was to kill.”

The family of one of the teenagers said: “We would like to take this opportunity to thank all those who have assisted in our son’s recovery.”

The family of the other boy said: “I am looking forward to my family moving on now that the trial is over, and I hope my son will continue his recovery and have a good future ahead.”

Bart Wielenga, the head of Blundell’s School, said: “We will continue to make counselling available to any staff or pupils who feel in need of additional support.

“I have been very clear with the pupils that this is not an incident we whisper about or have to be ashamed of. It is part of our narrative, our shared story.”