Garage boss and cannabis farmer Richard Spottiswood “choked the life” from Darren Bonner in a Northumberland caravan and left him naked in a nearby shallow grave after accusing his employee of leaking information to a rival drug dealer.

Mr Bonner, 24, from Sunderland, was discovered by a walker and died in hospital 16 days later on July 26, 2017, from irreversible brain damage after never regaining consciousness.

Spottiswood, 34, of Canterbury Way, Jarrow, was jailed for life after he was convicted by a jury in 2018 of murder following a two-week trial at Newcastle Crown Court.

Darren Bonner died 16 days after he was found dumped in a shallow grave in a field.

His girlfriend, Lucy Burn, then 30, of Burns Close, South Shields, was locked up for 30 months after admitting assisting an offender.

The Court of Appeal was told “that it introduced obvious and unacceptable prejudice into the trial” and “bolstered a weak prosecution case”.

Yet three judges have now rejected the killer’s appeal against his conviction and insisted that the Judge Ashurst had given the jury appropriate directions “limiting the potential relevance of this material”.

Spottiswood, however, did win a slight reduction in the 22-year minimum tariff imposed upon him as part of his life sentence.

Richard Spottiswood (inset) had been staying at the Cresswell Towers holiday park with his victim Darren Bonner before he attacked him

After identifying the starting point for the offence as 15 years behind bars, Judge Ashurst eventually added another seven years after outlining “aggravating factors” such as concealing Mr Bonner’s body.”

The Court of Appeal judges ruled that “together or separately” they did not warrant a seven-year increase and reduced the minimum term Spottiswood must serve to 20 years.

They concluded: “The degrading circumstances, the appellant’s selfishness in leaving a man in a shallow who was alive, the attempt to avoid detection, the involvement of his partner to cover up the crime and his criminal background were all in themselves serious features.

“But, as we have just observed, they did not justify a minimum term of 22 years.”After the pair’s conviction, Mr Bonner’s mother, Louise Tumilty, said her son was a "lovely, friendly, character" who was easily led.

Darren Bonner, centre, poses for a selfie with his killer Richard Spottiswood, left, and Lucy Burn, who was also jailed for assisting an offender.

Murderer Richard Spottiswood has lost his appeal against his conviction.

Darren Bonner was staying with Richard Spottiswood and Lucy Burn at Cresswell Towers caravan park when he was subjected to the fatal attack.

Jarrow murderer who left victim to die in shallow grave has sentence reduced