An elderly man with dementia who fatally stabbed his long-term neighbour following a row over a shared alleyway has been jailed for more than five years.Retired Transport for London (TfL) worker Derrick Brown, 74, killed Richard Brathwaite, 72, with a knife outside their homes in Wembley, north London, on March 21 2024.The court heard that the neighbours, who had lived next door to one another for more than 35 years, were once amicable but “frictions” had emerged following a dispute over a shared alleyway.At the time of the incident, Brown was suffering with undiagnosed dementia which had impaired his ability to form a rational judgment and exercise self-control, the court heard.After pleading guilty to manslaughter, Brown has now been handed an extended sentence comprising five years and four months’ imprisonment and five years on licence, after a hearing at Harrow Crown Court on Monday.Prosecutor Julian Christopher KC told the court that on the day of the incident, Mr Brathwaite was carrying out work on his car when Brown approached him and asked when he was going to “move the timber”.After pleading guilty to manslaughter, Brown has now been handed an extended sentence comprising five years and four months’ imprisonment and five years on licence, after a hearing at Harrow Crown Court on Monday. (Getty)It was heard that issues over an alleyway between the neighbours’ houses had caused “friction” in the past, and it is thought the comment referred to this.Afterwards, Brown went back to his house to pick up a kitchen knife which he had hidden under a recycling container in the weeks before over fears that neighbours in his street might try to harm him.The court heard that Brown then ran after his neighbour with the weapon and chased him into a garden.Mr Brathwaite’s wife Annetta heard shouting and ran over to where her husband was. She found him lying on the ground with blood on his shirt, it was heard.She ran back to call for help but was then “intercepted” by Brown, who held her against a parked car and punched her in the face.The woman managed to push him away and run inside her house to call the police.Another neighbour had come out into the street having heard the commotion and asked Brown what he was shouting about.Appearing angry, Brown responded and said words to the effect of: “I’ve had enough, they’re not listening, they need to move their things”.The neighbour asked what he was doing with the knife, to which Brown responded: “I’m going to kill them.”When emergency services arrived, Mr Brathwaite was found lying in the doorway to a house, bleeding from a stab wound to his chest which had penetrated his heart. He died at the scene.Mrs Brathwaite sustained a laceration to her top lip and a cut to the left of her forehead.Brown’s wife later told the police that he had been acting ‘strangely’ for some time and was constantly saying that Mr Brathwaite was trying to steal his house. (PA)After the events, Brown travelled to Lloyd’s bank which was said to be a normal part of his routine on a Thursday.He was arrested outside Wembley police station just after midday.Brown’s wife later told the police that he had been acting “strangely” for some time and was constantly saying that Mr Brathwaite was trying to steal his house.The elderly defendant previously pleaded guilty to the manslaughter of Mr Brathwaite, unlawful wounding of Mrs Brathwaite and having an article with a blade or point.His plea of manslaughter was accepted on the basis that his “ability to form a rational judgment and exercise self-control was substantially impaired by the dementia and persecutory delusions from which he was suffering at the time”, Mr Christopher told the court.Nina Grahame KC, mitigating, referred to the “robust” diagnosis of dementia given by medical professionals.She added: “That diagnosed dementia is, we submit, the only explanation for how this elderly man of previous good character, with no history of aggression or violence, committed these acts.”The lawyer said there was a background of “grievances” between the two neighbours over a shared alleyway which “developed as a result of the deteriorating mental health of Mr Brown”.Ms Grahame KC added that the “tragedy” of this case was that there was no diagnosis of dementia until the court proceedings.She referred to his career of three-and-a-half decades with TfL, adding: “He is not at base an angry or aggressive man. He is, through his life, a hardworking and loving husband and friend.”Sentencing him, Judge Anupama Thompson said she was imposing an extended sentence in order to protect the public after hearing that Brown’s delusional beliefs persist to this day.Speaking of the victim, she said: “It is clear that Mr Brathwaite was a gentle, generous, hardworking man, devoted to his family.“His family are struggling to comprehend his loss, a loss exacerbated by the fact he was killed in front of his home of so many years.”