A PUB doorman was caught on camera knocking out a young customer with one punch and leaving him unconscious in the gutter.

Gavin Naylor casually walked away and ended his shift at the Hartlepool bar after striking Steven McAllister a few days before Christmas.

A video of the attack - alleged by one-time football prospect Naylor to have been in self-defence - was seen by a jury yesterday.

Naylor, 28, denied a charge of assault occasioning actual bodily harm, but was convicted after a day-long trial at Teesside Crown Court.

The jury of seven women and five men took less than 20 minutes to find the Naylor guilty of the attack in the early hours of December 21.

Naylor, a former Manchester United trainee and personal trainer, was given bail until he is sentenced.

The video showed Naylor throw a left-hand punch at Mr McAllister, 20, outside of Bar Paris and Loons in Victoria Road.

Mr McAllister fell to the ground between two parked cars and lay motionless across the kerb as Naylor walked from the scene.

Moments earlier, the council-run closed-circuit television cameras captured the two men apparently having a dispute outside the bars.

Naylor said Mr McAllister had been abusive after he ushered him from Bar Paris at closing time, at 2am.

He alleged the customer - who admitted being drunk and said he remembered nothing after 9.30pm - had threatened him and his family.

After his arrest, Naylor told police he thought Mr McAllister had a knife or some jewellery in his hand, which he could have used to harm him.

Naylor, of Dundee Road, Hartlepool, also claimed Mr McAllister screamed at him: "I'm going to have your house burned down. I'll stab you."

He told the jury: "When we were stood there he was saying 'come on then, I'll stab you, I'll kill you' and his hands were moving all the time.

"I thought if he walked into the next bar - Loons - he would have been a threat not just to me but also to the pub . . . that's what I was wary about.

"I really believed he had a knife on him and he was threatening me with it . . . what I did disabled him from causing any kind of life-threatening injury."

Jolyon Perks, prosecuting, accused Naylor of causing the only life-threatening injury that night, and walking away with a "self-satisfied smirk" on his face.

The court heard Mr McAllister was unarmed, and knew nothing of the attack until he woke up in hospital.

He suffered multiple cuts to the inside of his mouth, and needed nine stitches to repair the injuries.