A GATECRASHER who seized a party goer in a headlock and slashed his throat with a Stanley knife has been sentenced to a ten year extended prison sentence.

David Lawler, who was branded dangerous and unstable, must serve a seven and a half year jail term before completing two and a half years on closely supervised licence.

He was convicted by a jury of cutting Benjamin Hanslip right across the front of his throat in an unprovoked attack that left the young man with a 12cm gash needing 12 stitches.

Lawler, 31, of Mallard Court, Lower Grange, Bradford, had a troubling history of violence, with convictions for possession of a bladed article, robbery, assault and violent disorder, Bradford Crown Court heard yesterday.

The Recorder of Bradford, Judge Roger Thomas QC, ruled that he posed a serious risk to the public after hearing he suffered from depression, anxiety and panic attacks, aggravated by excessive drinking.

Prosecutor David Hall said Lawler turned up uninvited at a flat in Crag Road, Windhill, Shipley, late on September 1, 2012.

He was drinking lager at 2am when he suddenly sprang at Mr Hanslip, grabbed him round the neck and cut his throat with a Stanley knife he seized from a nearby shelf.

Lawler was arrested after he was traced by DNA evidence he left on a lager can.

He denied the offence but was found guilty of wounding with intent to cause grievous bodily harm.

Since the attack, Lawler had served a 13 month jail sentence for violent disorder at an English Defence League demonstration.

He was banned from any EDL gathering after joining with five other men in "sustained, unprovoked racist violence".

Lawler's string of convictions began with possession of a butterfly knife when he was a youth.

In 2001, he was locked up for robbery and in 2005 he was cautioned by the police for making a threat to kill his partner.

Judge Thomas said it was "extraordinary" he was let off so lightly for arming himself with a knife while in drink while his partner locked herself in the bedroom.

Lawler's barrister, Austin Newman, said he was ashamed of what he had done to Mr Hanslip.

"It may be fortuitous but the injury was not the most serious example of its type. So far as we know, no damage was done to the underlying structures to the throat or neck. The victim made a relatively quick and good recovery," Mr Newman said.

Judge Thomas told Lawler: "You could so easily have killed Benjamin Hanslip. You caused him a superficial wound but what you did was draw a blade right across the front of his throat. It was a very nasty wound indeed on any view of it."

There was "no rhyme or reason whatsoever" for the attack.

After the case, Detective Constable Paul Maxwell, of Bradford District CID, said: "Lawler's actions were totally unprovoked and caused his victim to lose a lot of blood. We hope the sentence passed down today will send out a warning to others that violent crime will not be tolerated in West Yorkshire."