A disabled boy, left alone by his mother so she could go to work, died after two teenagers deliberately set fire to the house, a jury heard.

Damian Clough, 12, was killed by poisonous fumes in the slow-burning blaze at his home in Keighley on April 4 last year.

His mother, Julie Clough, said she left Damian asleep in his bedroom.

Fighting back tears, she told the Court she was mentally tired and had expected Damian’s sister back soon.

Mrs Clough, who worked as a part-time barmaid, said she was called back to the house in Kinara Close, Stockbridge, later that night because it was on fire.

Nasir Khan, 18, of Buxton Street, Dalton Lane, Keighley, and a 17-year-old youth, who cannot be named because of his age, deny Damian’s manslaughter.

Their trial, expected to last three weeks, started at Bradford Crown Court yesterday in front of Mr Justice Treacy.

Prosecutor Julian Goose QC alleged that Khan and the 17-year-old started two fires in the house before 10pm and ran off.

A neighbour raised the alarm at 11.28pm and firefighters were confronted by intense heat and black smoke.

Damian was found dead in his bedroom from inhaling smoke and toxic gases.

The family dog, also dead, was lying across the door to his room, Mr Goose said.

Experts said a naked flame was used to deliberately set fire to an armchair in the living room. Another fire, in the kitchen, went out after causing minor damage.

The jury heard that Damian had a number of disabilities. He was severely autistic and had severe learning difficulties.

His “highly obsessive” behaviour included shredding mattresses and wallpaper. Damian could not be left to sleep with his bedroom door open and he had broken off the internal handle.

Mr Goose said Damian’s condition meant he was unable to react to any danger.

His mother, who was his main carer, never usually left him in the house alone. She went to work on the night of the blaze after settling him and giving him his medication.

Mr Goose told the jury: “With the support of the local authority social services department and the housing association, Julie Clough was trying to cope the best she could in an extremely difficult situation. The fact remains, however, that when the defendants and their three friends entered the house, Damian was asleep and alone in his room from which he had no means of escape.”

The court heard that the five youths had bought alcohol and cigarettes and spent time at the Hollywood Bowl.

Mr Goose said they entered Damian’s home through the back door and made themselves at home.

Three of the teenagers then left, leaving the defendants in the house.

Mr Goose said: “The prosecution say that both of these defendants caused the death of Damian Clough by acting together in setting a fire or fires inside the house and then escaping.”

The trial continues