Stephen Alderton: Grandfather jailed for life after double murder ‘executions’ over boy’s custody

A man who shot dead his daughter’s ex-partner and her ex-partner’s father over the custody of his grandson has been sentenced to life in prison.

Stephen Alderton, 67, was sentenced at Cambridge Crown Court to life in prison with a minimum term of 25 years for the murders of father and son Gary Dunmore, 57, and Joshua Dunmore, 32.

He shot them dead in two villages six miles apart in Cambridgeshire in March this year using a Beretta shotgun.

Judge Mark Bishop described their murders as an “execution”.

He added: “You took the decision to take the law into your own hands and end the lives of two innocent men.”

Alderton, of no fixed address, was arrested by armed officers on a motorway hours after the shooting.

He told police at the time that “sometimes you have to do what you have to do even if it’s wrong in the eyes of the law”, according to prosecutor Pater Gair.

‘Always a plan B’

The court heard how Joshua Dunmore and Alderton’s daughter, Samantha Stephen, had split shortly after the birth of their son.

In 2020, she remarried an American national who served with the US Air Force.

When he was redeployed back to the US, the couple asked the family courts for permission to bring the child with them.

However, Joshua opposed the application and on 27 March – two days before the shootings – the court made an interim ruling the child could not be taken out of the country, Mr Gair said.

Prior to the ruling, Alderton had written in text messages that he would “override any court decision” and that there was “always a plan B”.

‘I don’t know what happened to me’

Alderton, a former chartered quantity surveyor, shot the two men with his Beretta shotgun on 29 March this year.

He killed Joshua at his home in Bluntisham, and Gary at his home six miles away in Sutton, Cambridgeshire.

The court heard how Alderton, a widower who was living in a motorhome at the time, had later written a letter in which he said he was “not the person” the court battle had “driven me to become”.

“I’ve never been a violent person, I do not have a criminal record,” he wrote.

“I’ve been a respectable, law-abiding citizen all my life.

“What happened to me on 29 March, I do not know.”

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Alderton pleaded guilty to both murders at an earlier hearing.

In sentencing, Judge Bishop said Alderton carried out the killings over his “distorted beliefs” about the family court proceedings “following what was an interim and not final hearing on 27 March”.

As Alderton was led down to the cells, a family member of the two dead men swore and shouted “rot in prison”, which was followed by brief applause.

‘Devoted father and loving uncle’

The family of Gary and Joshua Dunmore made no comment following Alderton’s sentencing on Monday.

They previously paid tribute to the “devoted” father and son in a statement released by police.

“Josh was a devoted father and a loving uncle,” they said.

“He was a wonderful son and brother and leaves behind an extensive group of family and friends. He will be deeply missed and the devastation this has caused will never heal.

“Gary was the most devoted son, brother, dad, and grandad, who gave everything for those he loved.

“He was a gentle and generous person who always put others before himself, and he’ll be massively missed by his family and all those who knew and loved him.”