In 1983 Kieran Kelly went to Clapham Common looking for drink money with a friend, Paul McManus, and threatened a seventy-five-year-old man until he handed over his watch and wedding ring. The man called the police. They could not find the watch or the ring, but they arrested both men for being drunk and disorderly and took them to Clapham police station, where a newly appointed sergeant, Chris Lynch, had them searched and put in a cell to sober up. The cell already held William Boyd, drunk, asleep and snoring. Kelly told him several times to shut up, and then took off his scarf and socks and strangled him. Some accounts say he also stamped on Boyd's head. Kelly was fifty-three.
He was from Rathdowney, County Laois. He joined the British Army and was dishonorably discharged in 1951 for going absent without leave, moved back and forth between Dublin and London for years and settled in London in about 1960. There he married, had several children and worked in construction, until his drinking cost him his home and his marriage. He spent time in Broadmoor Hospital. For years he lived among the gangs of homeless drinkers in the parks of south London, a slight man who had to assert himself. "He was an alcoholic," said Geoff Platt, one of the detectives who interviewed him. "He was looking over his shoulder his whole life."
Questioned about Boyd, Kelly calmly confessed to that killing and then to a series of others going back some thirty years. In taped interviews he described killing people by poisoning, beating and strangling, by setting them on fire, and by pushing them into the path of trains on the London Underground, mostly on the Northern line. Platt, who was skeptical at first, found that Kelly had been present at the scenes of several deaths on the Underground that had been recorded as suicides. Platt received a commendation for his work on the investigation.
In June 1984 Kelly was convicted of the murder of Hector Fisher, another homeless man, found dead in a churchyard on Clapham Common in 1975, and of the manslaughter of William Boyd. Like Kelly, both victims were homeless alcoholics living in the parks of south London. He was sentenced to life, and he died in 2001 at HMP Frankland in Durham.
Nothing beyond those two deaths was ever brought to court. In 2015 Platt published a book, The London Underground Serial Killer, arguing that Kelly may have killed as many as thirty-one people. The British Transport Police said that given the time that had passed, the claims would be difficult to substantiate without further evidence, and invited Platt to submit what he had. The original audio of Kelly's 1983 confession was later used in an RTÉ podcast and television series, The Nobody Zone, and in a 2024 documentary, The London Underground Killer. Whether his confessions were true, and how many, has never been established.