Three officers were shot dead and two others crippled for life by a gang of eastern European anarchists during a bungled burglary in Houndsditch in the City of London in December 1910.
The murders led two and a half weeks later to the famous Siege of Sidney Street, in which two of the suspects were killed and a firefighter suffered fatal injuries.
Then-home secretary Sir Winston Churchill was in the huge crowd watching from the sidelines as hundreds of police officers and a company of Scots Guards engaged in a fierce gun battle with gang members holed up in 100 Sidney Street in Stepney, east London.
Churchill was criticised for putting himself in danger by attending the siege, although historians dismiss accounts suggesting that one of the bullets passed through his top hat.
One of the gang, a Latvian Bolshevik called Jacob Peters, escaped hanging in London for the crimes and in 1917 returned to Russia, where he became deputy head of the secret police before apparently falling victim to Stalin's purges.
The case had echoes of some of today's most fiercely debated political issues, including immigration, arming police officers and interference in policing by politicians.