A Dumbarton thug who left a pensioner permanently brain damaged after punching him in the face has been jailed for three years.

Brian Warden, 36, launched the unprovoked attack on 77-year-old Owen Hagan 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.

The victim is still in care following the brutal attack, is confined to a wheelchair, and may never recover enough to even look after himself ever again.

Warden, who claims to have little recollection of the evening, handed himself in to police the next day following a media appeal, but claimed he was unaware if he had any involvement in the incident.

On January 25, dad-of-three Warden pleaded guilty at Glasgow Sheriff Court to assaulting Mr Hagan on March 23 last year, to his severe injury, permanent disfigurement and to the danger of his life.

On that occasion, Sheriff Norman Ritchie QC said he was considering sending the matter to the High Court for sentencing, but yesterday said he would not be doing so.

The sheriff acknowledged it was out of character for Warden, and also accepted claims that his remorse is genuine.

He said: "To his great misfortune Mr Hagan walked along the street oblivious to what was about to happen to him.

"The injuries suffered by him were truly devastating.

"One day when this today is a bad memory for you, Mr Hagan may well still be lying in that hospital bed."

He said Mr Hagan's quality of life has been diminished, and that it was Warden who was responsible.

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

Read more: Dumbarton thug Brian Warden attacked pensioner

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

Procurator fiscal depute Kathleen O’Donnell said that 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 walked 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.

“Whilst walking towards Mr Hagan, Warden 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 left 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.

Following a media appeal with descriptions of Warden and his wife, the thug went to the police office the following day to find out if he had any involvement.

Meanwhile, Mr Hagan was taken to Glasgow Royal Infirmary where he had a CT scan 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. In York, he was put 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.

She acknowledged the crime had "catastrophic consequences" and said: "He is devastated he has caused this harm to Mr Hagan and he appreciates that the consequences for Mr Hagan have been appalling."