Stephen Alderton: The Narcissism of the Revenge Murderer

Those who commit violent crime usually exhibit some form of personality disorder, diagnosed or otherwise. The murderer at the centre of this documentary appears to have been driven by one of the most common: narcissism.

| By: Oliver Daddow | Published: Apr 28, 2026

 

24 Hours in Police Custody: A Family Vendetta (Channel 4, UK)

Part 1: Monday 8 December 2025

Part 2: Tuesday 9 December 2025 

 

NB, contains spoilers.

Perpetrators of violent crime exhibit a range of different personality disorders. Among them, narcissism is one of the most common, with violent offenders putting their own needs and urges over and above those of their victims. This two-part special of 24 Hours in Police Custody got me thinking about the arrogance and self-righteousness of murderers motivated by revenge rather than, those who commit atrocities on the spur of the moment out of greed, hatred or jealousy. Advised by his lawyer to ‘No comment’ his way through lengthy police interviews, the main character in this story, Stephen Alderton, allied a stubborn reticence to speak with a haughty look that said to the interviewers, ‘What right do you have to question me?’ From the very moment of his arrest, Alderton had the demeanour of someone thoroughly confident he had acted out of a higher purpose, that mere mortals such as the police, or we as viewers, could not possibly grasp. Further research into Alderton’s case indicates he was driven by an appreciable level of narcissism that explains his lack of genuine contrition he showed. If you deem yourself above the law, you are unlikely to accept having to answer for your crimes in a court of law. Alderton therefore displayed the classic inverse relationship between narcissism and empathy: the greater the level of narcissism in someone’s personality, the less room they have to show the basic human empathy required to show true, as opposed to self-interested or performative, remorse. This blog unpacks how this apparent personality trait resulted in the tragic deaths of two totally innocent men: Gary Dunmore and his son Joshua Dunmore (inset picture, above).

At the time of his arrest, Alderton, then 67 years of age, was widely seen to be an upstanding member of the Cambridgeshire community. He had been a chartered quantity surveyor for many years, a self-proclaimed family man, and doting grandfather to his daughter’s children. He had never previously been in trouble with the police. As the Crown prosecution barrister argued at his trial, ‘it’s clear that the events were triggered by an ongoing family court case’–a custody battle between Alderton’s daughter and her former partner, 32-year old Joshua Dunmore. They were in and out of the family courts for years because Joshua’s former partner wanted to take their son to the US to live with her new partner, which Dunmore opposed. Alderton’s wife had died in 2019, and he was funding his daughter’s legal fees using funds from the sale of their former home. At the time of his arrest Alderton had no fixed abode; he was living in a motorhome on a temporary site in Cambridgeshire

On the evening of 29 March 2023, Alderton shot Dunmore twice in the hallway of Dumore’s home in Bluntisham, near Huntingdon. He then calmly placed his shotgun on the backseat of his car, drove six miles to Sutton, near Ely, and the home of 57-year old Gary Dunmore, Josh’s father, who Alderton shot three times with the same Beretta. The murders took place approximately 30 minutes apart. Alderton was arrested by armed police officers that same night, driving his motorhome along the M5 motorway. He was later charged with carrying out two cold-blooded shootings using the Beretta shotgun. As per the regulations in current UK firearms law, Alderton possessed a firearms certificate to hold the Beretta, and he had been certified to buy ammunition,. In other words, the police and relevant authorities had no cause for concern about Alderton’s mental or emotional capacity to hold a firearm over a period of several years.

Writing as someone whose own father was murdered by a shotgun (late night knock on the door; bang, bang; the victim bleeding out dead at the scene) the most distressing part of watching the documentary came during the CCTV footage of the second shooting. We do not see the shooting itself. However, we do see the door open and a shaft of hall light streaming onto the drive. There are two bangs. We hear Gary crying out ‘Ah’ as he falls to the ground. There is a pause, then a plaintive ‘Help’. This is followed by another single shot, then silence. That mere seconds-long footage sent a chill down my spine. One cannot begin to imagine what the victims must feel and think at the moment their lives are summarily and bloodily ended, in this case by someone known to victims, even if they were not on good terms. The documentary juxtaposes the CCTV footage of the shooting with that from earlier in the day, showing both men happily going about their daily lives: Josh seeing his son, Gary parking his van on the drive after work and putting out his wheelie bin. Here were two totally normal lives, needlessly ended by one man’s vengeful spirit.

The unsettling paradox at the heart of the case is that Alderton’s self-identity was entirely constructed around being a committed father and loving grandfather, yet he saw fit to end the lives of two family men he clearly saw as less deserving than himself of the basic human right to life. It seems to me that a psychological profiler might, in part, attribute [note: not justify] Alderton’s actions as evidence of a Narcissistic Personality Disorder (NPD). Two components of NPD are a sense of feeling superior to others, and a lack of empathy. Jack Hansen captures it thus: ‘Narcissists often believe they are superior and entitled to special treatment. This entitlement can escalate to aggression if their desires are not met’. People exhibiting NPD can be highly manipulative, with other humans existing merely to serve the narcissist’s needs and desires, like pawns in a game of chess. When they perceive that they may have lost control over a situation, the narcissist may resort to coercion, aggression or outright violence. Furthermore, ‘Instead of taking responsibility for their actions, narcissists tend to shift blame onto others. This avoidance of accountability can lead to hostile outbursts and aggressive behaviors’. All such features of NPD resonate with Alderton’s case.

As outsiders we are unable to read what the professional psychologists made of Alderton in his pre-sentence criminal psychological assessment, the Pre-Sentence Report. However, certain NPD traits do seem to underlie his thoughts and actions. Awaiting trial, Alderton wrote a letter attempting to explain and justify his actions: ‘If I could turn back time I would. I regret there are not enough words of remorse I can offer to the families affected by this crime … I’ve never been a violent person, I do not have a criminal record … What happened to me on 29 March, I do not know’. Note the phrasing, ‘What happened to me’. Alderton has reallocated blame away from himself and onto some inexplicable outside force. He went on to outline why he was ‘not the person that this conflict and the family courts have driven me to become’. Here we have more blame-shifting: ‘Driven me to become’. Then we have the sense of superiority and case for special treatment. Alderton explained to police, ‘sometimes you have to do what you have to do even if it’s wrong in the eyes of the law’.

 

 

Alderton’s self-serving narcissism also seems to have been growing for a number of months in the build-up to the murders. For he had clearly been moving towards a more extreme solution for many months, undermining his tendentious clam that he was possessed by a strange power for a temporary period of red mist on 29 March 2023. In a series of text messages to his daughter, in particular, Alderton indicated he would override any court decision that went against his family with a ‘Plan B’. In one message in 2022 he wrote ‘I’ve a shortlist of people I intend to murder’. No one pushed back on his increasingly violent rhetoric or thought to question him about what he might be planning. Maybe they saw it as bluster, but their obliging silence seems to have emboldened Alderton. Silence rather than collusion did at least prevent his daughter being charged with conspiracy to murder, which, as the investigation processed and their telephone messages studied, the police did discuss as a possibility with the Crown Prosecution Service.

The triggering event for Alderton was a family court hearing on 27 March 2023, which was an interim not a final hearing. Alderton fatally misinterpreted the meaning of the court decision that day, just 48 hours before the murders. Deciding the legalities had spiralled out of his control, Alderton put his bloody Plan B into action. Despite his reticence to explain himself in police interviews, he at least had the good grace to plead guilty to the killings, saving the co-bereaved the ordeal of a lengthy and painful trial. At Cambridge Crown Court in October 2023, Stephen Alderton was sentenced to life imprisonment, to serve a minimum term of 25 years in prison. Highlighting the level of planning that went into the murders, sentencing judge Mark Bishop described them as a calculated and cold-hearted ‘execution’. Bishop went on: ‘You took the decision to take the law into your own hands and end the lives of two innocent men’. In her victim impact statement, Gary Dunmore’s mother, Jane Phillips, said: ‘Both were killed in the most vicious, cowardly way with no opportunity for self-defence’. Joshua Dunmore’s mother Mandy Seamark, said ‘words cannot describe the devastation’ Alderton’s actions had caused.

The Solicitor General, Robert Courts, judged the initial sentence to have been unduly lenient and referred Alderton’s sentence to the Court of Appeal: ‘Stephen Alderton’s brutal killing spree has ripped apart a family. His despicable acts of violence are deplorable’. The Court of Appeal agreed with the Solicitor General. On 23 January 2024, it extended Alderton’s minimum term behind bars to 30 years. The Court of Appeal’s decision underlined, as Alderton’s defence barrister had previously pointed out, that Alderton was ‘realistic enough to know... he will never be released from prison’. Whether this narcissistic character will ever have the capacity to feel or express genuine remorse must strongly be doubted. His blame-shifting onto others speaks to a lack of contrition that will forever hamper the attempts by Joshua and Gary’s families and friends to achieve closure on their needless deaths. Alderton’s crimes show how indulging someone with NPD can lead to violent outcomes, if they are not recognised and/or acted upon. Greater public understanding of NPD could go some way to heading off more such crimes, so it can be tackled at earlier stages in someone’s life. I welcome your thoughts on this documentary through my website contact page.

 

Image credits:

1. Cambridge Police

2. Terry Harris