An Afghanistan veteran who stabbed his neighbours to death while their young children slept upstairs following a long-running dispute over parking has been jailed for at least 38 years.

Collin Reeves knifed Stephen and Jennifer Chapple six times each at their home in Dragon Rise, Norton Fitzwarren, near Taunton in Somerset, on the evening of November 21 last year.

Reeves, also of Dragon Rise, had been involved in a row with the couple over designated parking on the new-build housing development since the previous May.

The 35-year-old former Royal Engineer used the ceremonial dagger given to him when he left the Army to kill the couple.

Reeves himself called the police just a few minutes after the killings to confess what he had done, but later denied murder, claiming he was only guilty of manslaughter due to diminished responsibility.

But two forensic psychiatrists found he was not suffering from psychosis or acute post-traumatic stress disorder, and diagnosed him with only mild to moderate depression.

A jury at Bristol Crown Court heard that Reeves had also been having trouble in his own marriage, and that less than an hour before he stabbed the Chapples his wife had asked for a trial separation.

Reeves was unanimously convicted of murder last Friday after jurors deliberated for five hours and 21 minutes.

Jailing Reeves for life with a minimum term of 38 years, Mr Justice Garnham said the killings had “torn the heart out of two perfectly normal, decent families”.

“You left (Mr and Mrs Chapple) on the floor bleeding to death, and all of the time their two children were asleep upstairs,” the judge said.

“Your murderous behaviour left them orphans. They were put to bed that night by their parents and they would never see them again. The harm you did those two innocent children is incalculable.”

Mr Justice Garnham said that, at the same time, Reeves had inflicted enormous damage on his own daughters, who will now grow up without their father.

Mrs Chapple’s mother, Ann Clayton, said in a victim impact statement: “For a mother to lose a child is something that causes never-ending pain, knowing there will forever be a darkness inside you, a light switched off that can never be replaced.”

She described her daughter as “an exuberant, caring, beautiful light in the world”.

In a highly unusual step, after sentence was passed Reeves’ mother, Lynn, stood up to give her own statement, blaming her son’s conviction on failings by the two psychiatrists who assessed him.

She claimed there should never have been a trial, and that his pleas to manslaughter should have been accepted, before she was stopped by the judge.

On the night of the murders, Reeves was caught on a security camera climbing the fence separating his garden from the victims’ garden, and entering through the back door.

A few seconds later Mrs Chapple can be heard screaming in terror, with Reeves shouting “Die, you f******, die”.

Mrs Chapple, 33, did not even have a chance to stand up from the sofa to defend herself, while Mr Chapple, 36, was found close to the back door.

The court heard that the Chapples and Reeves previously had a good relationship but it had deteriorated when Mrs Chapple learned to drive and bought a second car.

Rows over parking spaces escalated to the point that both Reeves’ wife Kayley and Mrs Chapple had told their friends they were anxious about bumping into each other on the school run.

Ten days before the killings, Reeves was caught on a doorbell camera approaching Mrs Chapple outside her house following an earlier exchange between her and Mrs Reeves.

He accuses Mrs Chapple of “f****** gobbing off, you cheeky little bitch”.

The victim replies: “She’s the one who started it, just f*** off”, to which he responds: “What’s that, you f****** c***, you fat bitch, you f****** … f****** c***?”

After the killings, Reeves was recorded in the background of the 999 call telling someone, believed to be his mother Lynn, “I couldn’t let her (or them) torment Kayley any more”.

Reeves said he had little memory of the incident but recalled sitting on the stairs in tears after the conversation with his wife.

He claimed he did not remember taking his dagger out of the picture frame in which it was usually displayed.

The defendant, who had previously recounted his fear of CCTV cameras and being under surveillance, said the next thing he recalled was a bright light coming on, and trying to get down on his front.

“I felt as though I had been seen or compromised – white light was a trigger when I was a soldier. When a light goes on or somebody sets off a flare, when that white light goes up something is going to happen,” Reeves said.

Asked what else he remembered, he said: “I had a feeling like it was me or them.”

Adam Feest QC, prosecuting, asked: “When your wife said you needed to have a separation, did you at least, in part, blame Jennifer because she had tormented (your wife)?”

He added: “’I can’t let her (or them) torment Kayley’ – I want to suggest that this is an accurate expression of why you went around to your neighbours that night. I’m going to suggest that’s the truth.”