Bellbottoms, Easy-Bake Ovens and the Beatles were big that year. But for certain thieves and the detectives who tried to track them down, The Great Train Robbery of 1963 was bigger, the largest cash theft of its time. Fifteen masked men were able to secure £2.6 million in British pounds from a Glasgow-London mail train, the equivalent of around $50 million today. While this is one of Britain’s best-known crimes of all time, what happened during and after the incident?

Gone in 30 minutes

A bank holiday weekend in Scotland made it all possible, resulting in a record amount of cash flow for the train, which was transporting notes ready to be dropped from circulation. A postal worker leaked this tantalizing fact to the gang. It was able to score quite quickly with this complete information about both the train and postal timetables.

According to a 2013 eyewitness account in The Bournemouth Echo on the crime’s 50th anniversary, gang members forced the train to stop by wiring a battery so that it covered the green light, turning it to red. They then beat driver Jack Mills with an iron bar so he’d drive the train 600 yards from its typical stop. There the robbers unloaded their haul, carrying 120 mail sacks down an embankment to two Range Rovers and a military truck in about 15 minutes. The thieves went to a barn at Leatherslade Farm and shared their loot. About an hour after the robbery, a train guard spotted the delay and put out the call for help.

One factor that enabled this speedy crime: Very little security. Only a sealed door accessible from inside the train and some unarmed guards kept the masked men from their quarry. And it took a full day for local police to ask Scotland Yard for assistance, which they did only after going farm-to-farm following leads and scouring the countryside for the loot and the crooks.

The almost as great train robber roundup

All of the U.K. and plenty of Americans and other foreigners were enthralled with the caper, nicknaming it The Great Train Robbery and sort of romanticizing the crime though it involved that brutal beating. The New York Times characterized it as a “British Western.” But the gang had still employed violence and thievery, so British detectives tracked them down with every expert at their disposal.

The first break in the case came with a tip to examine the farm, where the getaway vehicles were uncovered. Some of the criminals were experienced, though, and had removed fingerprints. The police famously found others on a Monopoly game and a bottle of catsup, however. Within a week, the first arrest had been made in Bournemouth and by January of the following year, 12 of the suspected 16 Great Train Robbers were on trial.

These gang members included old hands Gordon Goody and Buster Edwards, who parlayed the postal worker’s tipoff with the help of Bruce Reynolds, Ronnie Biggs, Charlie Wilson, and Roy James. During preparation, the gangsters also included some members of the South Coast Raiders, a gang whose expertise lied in rigging train signals to stop engines.

The sentencing topped out at a 30-year prison sentence and some of the men were able to plea bargain down to 14 years. From 1963 to 1968, the authorities had all the robbers arrested. Unfortunately, the post worker who leaked the information was never captured by the police nor were they ever able to determine who coshed the train’s conductor.

Most of the money was gone for good

The bounty from the notorious 1963 crime was believed to have been split into roughly equal shares, with smaller amounts given to gang members who played a lesser role in the crime. Most of the money was never recovered.