Keith Henry Blakelock, a London Metropolitan Police constable, was murdered on 6 October 1985 during rioting at the Broadwater Farm housing estate in Tottenham, north London. The riot broke out after Cynthia Jarrett died of heart failure during a police search of her home, and took place against a backdrop of unrest in several English cities and a breakdown of relations between the police and some people in the Black community.PC Blakelock had been assigned, on the night of his death, to Serial 502, a unit of 11 constables and one sergeant, dispatched to protect firefighters who were themselves under attack. When the rioters forced the officers back, Blakelock stumbled and fell. Surrounded by a mob of around 50 people, he received over 40 injuries inflicted by machetes or similar weapons, and was found with a six-inch-long knife in his neck, buried up to the hilt. He was the third officer to be killed in a riot in the London area. The first occurred in 1833, when PC Robert Culley was stabbed to death in the Coldbath Fields riot, Monday, 13 May 1833, found by the jury to be justifiable homicide. The second occurred in 1919, when Station Sergeant Thomas Green was struck with a metal bar in the Epsom riot.

Detectives came under enormous pressure to find those responsible. Faced with a lack of scientific evidence—because for several hours it had not been possible to secure the crime scene—police officers arrested 359 people, interviewed most of them without lawyers, and laid charges based on untaped confessions. Three adults and three youths were charged with the murder; the adults, Winston Silcott, Engin Raghip and Mark Braithwaite (the "Tottenham Three"), were convicted in 1987. A widely supported campaign arose to overturn the convictions, which were quashed in 1991 when scientific testing cast doubt on the authenticity of detectives' notes of an interview in which Silcott appeared to incriminate himself. Two detectives were charged in 1992 with perverting the course of justice and were acquitted in 1994.Police re-opened the murder inquiry in 1992 and again in 2003. Ten men were arrested in 2010 on suspicion of murder, and in 2013 one of them, Nicholas Jacobs, became the seventh person to be charged with Blakelock's murder, based largely on evidence gathered during the 1992 inquiry. He was found not guilty in April 2014.Blakelock and the other constables of Serial 502 were awarded the Queen's Gallantry Medal for bravery in 1988. Their sergeant, David Pengelly, who—armed only with a shield and truncheon—placed himself in front of the crowd in an effort to save Blakelock and another officer, received the George Medal, awarded for acts of great bravery.