A DUMBARTON thug who punched a pensioner on the street without warning and left him with permanent brain damage is behind bars.

Brian Warden, 36, attacked 77-year-old Owen Hagan in the unprovoked attack as the pensioner walked past him and his wife in the street.

The brute had earlier been seen arguing with his partner and was spotted punching and head butting walls.

He smacked the retired school teacher and continued on, leaving the injured man unconscious and bleeding on the street.

Warden, who claims to have little recollection of the evening, handed himself in to police the next day after a media appeal, to see if he had any involvement.

The father-of-three, from Dumbarton, pleaded guilty at Glasgow Sheriff Court on Friday to assaulting Mr Hagan on March 23, 2018, to his severe injury, permanent disfigurement and to the danger of his life.

Sheriff Norman Ritchie QC told Warden’s lawyer, Clare Ryan: "Your client has destroyed a man’s life."

He also said he is considering remitting the case to the High Court for sentence and said: "My first thought is this is the wrong forum."

Mr Hagan was described in court as "very active and independent and enjoyed walking and learning new languages".

The court heard Warden and his wife were in town from 12pm and were drunk after a day of drinking.

Procurator fiscal depute Kathleen O’Donnell said around 9.30pm a number of people saw the couple arguing.

Warden was seen to punch and head butt walls in Bath Lane in Glasgow city centre.

He stopped and sat at the corner of West Campbell Street and Bath Street with his head in his hands in an "agitated manner", then stood up and was followed by his wife along Bath Street.

Miss O’Donnell said: "At this time, Mr Hagan who had been out drinking in Glasgow was heading along Bath Street in the direction of Warden and his wife.

"There was no interaction between Warden and Mr Hagan.

"While walking towards Mr Hagan, Warden then drew his arm back and punched Mr Hagan without warning, striking him to the head area causing him to fall backwards and strike his head on the pavement.

"Warden continued on his way without breaking his stride."

The attack was seen by a number of people, who went to help Mr Hagan who was lying on the ground unconscious and bleeding from his ears.

Warden and his wife continued in the same direction along Bath Street, towards the city centre.

Mrs Warden told a woman that "he was not a bad guy" and that she had got him riled up.

A witness took a photograph of Mrs Warden, that was later passed to the police.

After a media appeal with descriptions of Warden and his wife, he went to the police office the following day to find out if he had any involvement and claims he has little recollection.

Mr Hagan was taken to Glasgow Royal Infirmary where he had a CT which revealed a fractured skull and bleed to the brain.

He was put on constant observations and the following morning his condition deteriorated and was deemed "life threatening".

As his condition improved he was able to speak to hospital staff, and his son but he later began to worsen and became increasingly disorientated and confused.

In May, last year, he was transferred from Glasgow to neurosurgery at York Hospital to be closer to his GP son, into the care of consultant neurologist Dr Philip Duffey.

Miss O’Donnell added: "Mr Duffey states that Mr Hagan is unlikely to improve to any significant level and he has been left with permanent brain damage.

"He will require assistance in every aspect of his care and is unlikely to ever be able to care for himself independently again or be able to leave hospital care."

The OAP, now wheelchair bound, is in danger of taking seizures and will have to sell his home to pay for his care at £950 per week.

Miss Ryan, defending, said Warden has no previous convictions and is of good character, with three children.

Sheriff Ritchie deferred sentence for reports and remanded Warden in custody.

He told him: "Your wife commented you’re a good man, that may well be right.

"This was not a good deed, this was a horrendous thing you did.

"You have caused the end of this active man’s life, a man who has given a public service."