A detective is facing jail today after leaving a man brain damaged when he felled him with a single punch.

Graeme McMillan, 44, a father-of-three, was sent crashing to the ground when he sprang to the defence of his wife following a comment from a stag night reveller.

Mr McMillan's wife, Carole, broke down in tears as a jury at Newcastle Crown Court found her husband's attacker guilty yesterday.

As Detective Constable John Beresford, 44, stood in the dock in shame the court heard how his brutal attack had destroyed his victim's life.

In a statement to the court, Mrs McMillan, 40, said: "The Graeme I knew and loved died that night and I was left with a total stranger in Graeme's body."

The court heard how Mr and Mrs McMillan were enjoying a night out on Newcastle's packed Quayside when the tragedy happened on June 8 last year.

John Evans, prosecuting, said the couple were making their way towards a taxi rank when they heard someone make lewd comments about Mrs McMillan.

When Mr McMillan told the group they should show some respect, he was punched to the ground and lay on the pavement with blood pouring from his ear.

The court heard how the tool fitter was taken to Newcastle General Hospital's high dependency unit where his condition deteriorated so badly that part of his brain had to be removed. He has been left permanently brain damaged.

The court heard how Beresford had been out since lunchtime with colleagues from the Durham force celebrating an impending marriage.

Mr and Mrs McMillan had enjoyed a night out on the Quayside with another couple and had decided to take a taxi to another part of the town.

Mrs McMillan, of Kingston Park, Newcastle, told how she knelt by her husband of five years and tried to wake him. Her husband spent weeks in intensive care in a coma.

The court heard how, as a result of the attack, the couple have been forced to separate for the safety of their children because of Mr McMillan's now bizarre behaviour.

Beresford, of Chester-le-Street, County Durham, had been on a drink binge for nine hours before the attack, the court heard.

When confronted, he admitted striking Mr McMillan but claimed that he had hit out in self-defence.

But the jury believed Mrs McMillan's version of events and Beresford was found guilty on a majority verdict after more than three hours of deliberations.

He was granted bail and will be sentenced today after being convicted of grievous bodily harm.