A drunken, knife-wielding man who launched a tirade of racist abuse at a teenager has been jailed for a year.

Matthew Sherratt, 20, had been drinking so heavily at a barbecue that he could not recall the incident on an evening in May.

As well as brandishing a large butcher's knife which had been tucked into his waistband Sherratt also assaulted a teenage girl and a 16-year-old boy.

James Bromige, prosecuting, told Swindon Crown Court yesterday that the victims, one of whom is a 17-year-old Asian, were all strangers to Sherratt.

The three boys and a girl were in Cherry Gardens, Trowbridge, on the way home from McDonald's at about 8.45pm when they saw the defendant, who looked angry.

After starting on another lad Sherratt threatened the Asian boy, asking to fight him, and when he replied 'who do you think you are talking to,' he fired off a racist tirade.

Mr Bromige said: "He said he outwardly laughed this off but inwardly he was disgusted by what he told him."

The defendant kept ranting that one of the others had punched his sister, and they were asking who she was when he punched one of the boys in the face.

When he girl said 'How old are you? You've hit a 16-year-old', he threatened the Asian youth and lifted his shirt showing a knife in his waistband.

"He said 'Trust me, I don't want to say one more word or I'll stab you, you know I will'," Mr Bromige said.

He then punched the girl, leaving her in tears, and as the group ran off, produced a 10-inch knife with a curved blade.

Seeing the trouble outside, a local resident let the four teenagers into his house while the police were called.

Sherratt, of Spinners Close, pleaded guilty to a racially aggravated public order offence, possessing an offensive weapon and two common assaults.

Matthew Scott, defending, said his client recalled nothing of the incident as he had drunk so much at a barbecue and did not know victims or why he targeted them.

He said he feared he was following the path of his father, grandfather and uncle and becoming an alcoholic and was trying to address the problem.

When he was younger he said he was diagnosed with attention deficit hyperactivity disorder and being on the Asperger's spectrum.

He added that his client was not racist telling the court: "Half of his family are black. He says he has no racial prejudice in him at all."

Jailing him, Judge Douglas Field said: "You were drunk, you had a wicked looking knife in your trouser band. You confronted these young people.

"You abused them, threatened and hit the young girl. You racially abused in the most disgusting way.

"On the evidence in front of me you took that knife deliberately to intimidate and frighten them.

"Notwithstanding your terrible background there is no excuse for this inexcusable intolerable behaviour."