Accountant Abdul Janjirker has been cleared of killing a teenager after telling an Old Bailey jury he was trying to protect his family from a racist attack.

The prosecution had told the court that Mr Janjirker, 50, of Healey Avenue, High Wycombe, chairman of a race relations group, stabbed Gary Allsopp, 17, in the throat after a traffic dispute in Southall, West London, on April 23 last year.

Mr Janjirker said he could not remember causing the fatal wound because his mind went blank after he was hit on the head with a brick.

Mr Allsopp lost a catastrophic amount of blood and died shortly after collapsing at the roadside.

It was alleged that Mr Janjirker had admitted at the scene that he had stabbed Mr Allsopp, from Southall, and that he had been first to brandish a knife.

Mr Janjirker, a father of three, denied in court that he had made any confession. Mr Janjirker's case was that he was acting as an automaton his actions not connected with his mind after he was hit on the head. It was therefore argued that he was not criminally responsible for Mr Allsopp's death.

Earlier this year a jury acquitted Mr Janjirker of murder, but failed to reach a verdict in respect of a manslaughter charge and a retrial was ordered. The jury yesterday took 90 minutes to clear Mr Janjirker of that charge.

Michael Wolkind, defending, said in his closing speech that Mr Janjirker was not "a cold, clinical assassin.

He added: "Mr Janjirker has post-traumatic stress disorder. He needs much treatment before he can appreciate that he has caused the death of a young man."

Outside the court, Mr Janjirker said: Im relieved that this nightmare is over.

Now I will offer a prayer. Ill just sit back and enjoy the company of my family and friends for a while.

Clearly drained by the stress of two trials, he added: Id like to thank the people who have supported me.

Gary Allsopp's mother, who was in tears outside the court, refused to comment.