A 13-year-old schoolboy from Watford has been left with brain damage after a bully assaulted him in a ‘happy slap’ attack at school.

Tommy Allery was filmed by another student as he was beaten up in a corridor at Kings Langley School.

In the disturbing footage, Tommy is hit in the temple before collapsing - suffering a seizure caused by a bleed on the brain.

Speaking to the Sun this week, his dad John Allery, said: “It was the hardest thing I’ve ever had to see.

"I just burst into tears when I saw him in the recovery room, I couldn’t handle it.

"His mum stayed by his side the whole time, I don’t know how she did it. She was so strong.”

Once he was stabilised, he was sent to Great Ormond Street Hospital’s neurosurgery unit for further life-saving operations and remained in a coma for 12 days.

Tommy, who needed a wheelchair and had to be fed through a tube while in hospital, will never be able to drive, fly, or play his favourite sports ever again.

He has been fitted with a shunt that drains fluid from his brain, heart and stomach.

His mother, Clo Marques, said: “I’m never going to get my Tommy back. I’ve got this new Tommy, but not my old one.

"I miss him so much. He can’t remember if he’s had a good day, what he had for breakfast.

“I know he’ll never be the same Tommy he was. He should be out chasing girls but he’s just at home in bed all day.

"It’s ruined the best years of his life.”

Gary Lewis, headteacher at Kings Langley School, said the incident was isolated and the school has been supporting the family.

He said Tommy is expected back at school in September.

His 14-year-old attacker, who cannot be named for legal reasons, admitted GBH at St Albans Youth Court on May 27.

He had earlier pleaded guilty to grievous bodily harm on January 6, 2016.

He was sentenced to a 12 month referral order and must pay £85 in court costs and a £15 victim surcharge.