A gang of 15 men rigged a railway signal, stopped a night mail train with a battery-powered fake red light, and walked away with millions in untraceable cash.
In the early hours of August 8, 1963, a gang of 15 to 17 men led by Bruce Reynolds ambushed a Royal Mail train traveling from Glasgow to London at Bridego Railway Bridge near Ledburn, Buckinghamshire.
The gang rigged the trackside signal lights with a battery and glove to display a false red stop signal, tricking the driver into halting the train in the middle of the countryside.
Train driver Jack Mills was struck on the head with a metal bar and seriously injured; he never fully recovered and was unable to work again, one of the few instances of violence in the robbery.
In just under 30 minutes, the gang formed a human chain to unload 120 mail sacks stuffed with cash, making off with £2.61 million, worth roughly £50 million in today's money.
The gang hid out at Leatherslade Farm, 27 miles from the crime scene, believing they had time to disperse before police made the connection.
Investigators found the farm just five days later and lifted a trove of fingerprints from items left behind, including, famously, a Monopoly board the gang had played with while waiting.
Most of the gang were eventually caught and sentenced to 30 years in prison in 1964, an extraordinarily harsh sentence for a crime with no fatalities, meant to send a message.
Several members escaped and became fugitives for decades: Charlie Wilson fled to Canada, Bruce Reynolds hid out in Mexico and France, and Ronnie Biggs famously escaped to Brazil, where he lived openly for years, mostly beyond the reach of British extradition.
The vast majority of the stolen money was never recovered, and the robbery became one of the most romanticized crimes in British history, inspiring numerous books, films, and television dramatizations.