A teenager drove his car off a cliff two weeks after he started using cannabis.

Chris Bull, 19, drove the Renault Clio through a fence and plunged 150ft to his death.

A coroner's suggestion that experimental drug use had upset the balance of his mind was today angrily rejected by his parents.

They have filed a complaint against Sussex Police, saying the force failed to act after milkman Mr Bull and his brothers were set upon by a gang of teenagers near the Palace Pier in Brighton in June last year.

They believe the effects of the attack led to a decline in their son's mental health.

Two weeks after the attack, Mr Bull drove a friend to the estate where they believed the gang members lived in an attempt to identify them. He crashed, injuring his friend.

Although he thought he would not face prosecution for the accident, a court summons arrived at the family home in Bramble Rise, Brighton, on Christmas Eve.

He feared a driving ban would cost him his job and his family says it was this which plunged him into deep despair.

East Sussex Coroner Alan Craze recorded a verdict of suicide, saying there was little doubt the teenager had deliberately taken his life.

Community psychiatric nurse Joan Cunden told the Eastbourne inquest Mr Bull began using cannabis a fortnight before his death. He had first tried the drug aged 15 but given it up. He had also experimented with ecstasy, amphetamine and cocaine.

He spent February 3 with his mother, Angela.

Mrs Bull said: "At about 9pm, as we were sitting having a burger in a cafe, I asked him what he was thinking about. He said, 'I'm thinking about how I can kill myself'.

"I said, 'No you can't, you have got to stop worrying about what everyone else is saying and doing'."

Mrs Bull last saw her son at 10.30pm. He left the family home at 11.05pm, travelled to cliffs at Keymer Avenue, Peacehaven, and drove over the edge.

His father, Ian, said: "The coroner seemed to concentrate on the drugs but I think that deflected from the other things that went wrong.

"Chris really blamed himself for his friend's injuries and it was a real blow to learn he would have to go to court when he had already been told there would be no prosecution.

"He wasn't into drugs as such - he just smoked the occasional joint.

"We didn't like it but he had stopped doing it for the last couple of years.

"We couldn't believe they brought up ecstasy.

"I think he took half a piece of ecstasy once two years ago.

"I don't think it has any relevance to what happened.

"The inquest made him sound like a habitual drug-taker, which he wasn't."

Mr Bull's problems led to an outpatient referral to Mill View Hospital in Nevill Avenue, Hove, in December last year.

Ms Cunden said Mr Bull sometimes spoke of suicidal thoughts but she did not consider he required in-patient psychiatric care.

She said that at their final meeting his mood was flat. He was concerned about his job and his relationship with his girlfriend.

Mr Craze said: "I'm satisfied so that I'm sure beyond all reasonable doubt that Christopher drove the vehicle off the cliffs with the intention of killing himself while the balance in his mind was disturbed."

Mr Bull's parents accepted the verdict but were angered by the focus placed on his use of drugs.

His father said: "Life will never be the same. We are without him for the rest of our lives. Chris became an uncle recently but he wasn't here to see his new nephew."