Netflix’s The Diamond Heist police trap and how robbers were caught explained (2025)

Netflix's The Diamond Heist tells the real-life story of an attempted £350 million robbery.

The Millennium Dome Raid would have made history as one of Britain's biggest heists, had it been successful. The audacious robbery rocked London over 20 years ago, following the launch of the Millennium Dome (present day O2 arena).

The Greenwich-based dome drew public attention for its various exhibitions, including a diamond display hosted by De Beers, one of the leading diamond companies in the world. At the centre of their £350 million jewel collection was the Millennium Star, a 203-carat stone, which caught the eye of a local gang.

Netflix dives into this infamous attempted raid in the new documentary, The Diamond Heist, available to stream now. The three-part series features a personal account of the events leading up the raid from one of the real-life perpetrators.

Although the gang had an intricate plan, they did not anticipate the Metropolitan Police's Flying Squad would be laying in wait for them at the crime scene. But how did the officers know where the thieves would be?

First attempt

The police first encountered some of the gang members in February, nine months before the raid. They received reports of a group who attempted to rob a security van, carrying £10 million. The robbers notably had a lorry with a metal spike mounted on top of it, intended to pierce the the security van and grant them access to the money.

However, when they were away from the vehicle, an unassuming member of the public took the keys out of the ignition. This spoiled the robbers' plan and forced them to flee the scene, escaping via the Thames.

In July of the same year, a similar attempted robbery took place in Kent, but it was more successful. Unlike their last raid, the gang had now managed to ram into the van, but they fled when a police car interrupted their raid.

Surveillance

Following the two failed attempts, the police suspected there would be a third robbery. They soon pieced together that Lee Wenham's rural Kent farm was central to the plot, and placed it under 24-hour surveillance. Alongside cameras near the property, officers also followed Wenham's every move.

During their surveillance, they tailed Wenham to the Millennium Dome, where he visited the De Beers exhibit. Wenham was tasked with planning the heist, meaning he repeatedly visited the diamond display for research.

After multiple trips to the dome, the police suspected that the diamonds were the gang's next target, and started planning their own operation.

Day of heist

By November 7, the day of the heist, officers had a fool-proof plan top stop the raid.

There were officers stationed around the Thames to foil the speedboat getaway, which the group had used in their previous robberies. Inside the building, the firearms unit of the Met Police were ready for the attack, alongside officers disguised as dome employees.

Although they were expecting an attack, the officers did not expect the gang to ram a JCB digger into the building. However, they still had the upper hand.

Only two members of the gang, Robert Adams and William Cockram, entered the diamond vault and started attacking the diamond's glass casing with a sledgehammer and nail gun. At the same time, Aldo Ciarrocchi threw smoke grenades to create a diversion.

Had they secured the diamonds, the group had planned to escape through the Thames, but they did not get that far.

As they smashed their way into the display, the police jumped out from their hidden stations around the dome and arrested six out of the seven suspects. The last gang member to be arrested was Lee Wenham, who had been waiting for the rest of the group at his Kent farm.

The officers had also swapped the real diamonds for replicas just in case the operation was not successful. However, they swiftly apprehended the entire crew.

The gang were tried and sentenced at the Old Bailey.

The Diamond Heist is streaming now on Netflix.