A teenager who killed his “gentle” stepfather with a single punch during a row over pocket money has been acquitted of manslaughter.

The jury of seven men and five women returned a not guilty verdict after deliberating for six hours and 44 minutes.

Douglas Herridge had denied the manslaughter of 6ft 4in tall former national squash champion Colin Payne, claiming he acted in self-defence.

There were gasps from the public gallery as the verdict was given by the jury foreman.

Judge Jeremy Carey told jurors: “I have no doubt this has been a taxing case for you, as it would be for any jury because of the subject matter.

“The word tragedy is probably overused, not least in these courts, but this case can truly be described as a tragedy in my judgement.

“The deceased in this case was to everybody’s assessment a fine man, a distinguished amateur sportsman, a good father and decent and responsible member of society, and he came to an untimely death in circumstances which really were absolutely devastating.

“I have no doubt those who grieve his death do so because they loved him and loved him dearly. I don’t expect they will easily come to terms with the outcome of this case - and why should they?"

“I have no doubt too that the family of this defendant are finding the court process and its outcome difficult.

“What mother could possibly cope with the situation in which she has had to give evidence for the prosecution and the defendant is her natural child?

“These are very very difficult circumstances for all concerned.”

"The word tragedy is probably overused, not least in these courts, but this case can truly be described as a tragedy in my judgement" - Judge Jeremy Carey

The jury was directed by the judge to find the teenager not guilty of murder.

Maidstone Crown Court heard the 54-year-old businessman collapsed to the floor with “catastrophic” effect at his Dartford home on November 19 last year and died soon afterwards from a devastating brain injury.

The tragedy was witnessed by Herridge’s mother Ina, who told police Mr Payne “would not even harm a fly”.

The stepfather, who represented England at squash and won the over-50s British title, had himself told officers after an earlier incident at the house in Sackville Road with the teenager he “couldn’t fight his way out of a paper bag”.

“Mr Payne was fit and healthy,” prosecutor Richard Hearden told the jury of seven men and five women. “He was killed by his 17-year-old, now 18-year-old, stepson, who punched him during the final of many recent arguments.

“That single punch was catastrophic and led rapidly to Colin’s death. It was witnessed at first-hand by the defendant’s mother and Colin’s partner.”

Herridge’s mother, a risk assessor with the NHS, gave evidence for the prosecution from the witness box without being screened from the dock.

Mrs Herrige had not spoken to her son since her partner died but later sat with him outside the court.

She described how Mr Payne went slowly to the floor in the study after being struck on the left side of the face by her son.

Mr Hearnden told how Mrs Herridge’s parting and subsequent divorce from her husband David in 2011 caused tremendous “emotional turmoil” in Douglas, the younger of their two sons.

Herridge would become highly upset, angry and agitated.

There was an incident when he put his hands on his mother’s throat and others when he punched and kicked her and tried to push her down the stairs.

Herridge, who has been bailed to his father’s address in West Malling, claimed in evidence Mr Payne had his hands around his throat when he lashed out at him.

He said he threw one punch that missed and then threw a second which caught him on the side of the face.

Asked why he hit out, he replied: “Well, he had hold of me around the neck and all I wanted to do was get him off me.

“When I struck the second blow I was scared. I didn’t know what was going to happen. I had to defend myself. I remember him going slowly towards the ground.”

Herridge, who said he liked Mr Payne, added he could not believe it when told he had died.

The judge commended those in the public gallery during the trial for the restraint they had shown.

Trials, he said, were often disrupted by those who felt they had to demonstrate their anger and frustration.

“That has not happened in this trial,” he added.

Judge Carey had told jurors in his summing up of the case they must reach a just verdict and not worry about the consequences.

“Don’t be anxious about the outcome,” he said.