BBC Factual today announces The Gold: The Inside Story, a one-off documentary which hears from the detectives who investigated Britain’s biggest bullion heist and led the hunt for three tonnes of gold.

In November 1983, armed robbers stole £26 million worth of gold from the Brink’s-Mat security depot near London’s Heathrow airport. They escaped with 6,800 bars of gold with an equivalent value in today’s money of nearly £100 million. It was a race against time before the gold was smelted, disguised and sold back on the open market, fuelling criminal enterprise on an unprecedented scale.

Speaking on film for the first time since the robbery almost 40 years ago, Detective Chief Superintendent Brian Boyce, head of the investigation and DC Tony Yeoman, disclose the challenges they faced and the strategy they used in the hunt for the gold. They reveal how tragedy unfolded with the death of DC John Fordham as they staked out Kenneth Noye, one of the men at the epicentre of the gang transforming the gold into cash.

Archive footage and eyewitness testimony detail the cat-and-mouse chase across borders and continents and the tracking of a corrupt network of professionals, lawyers and accountants who helped to launder the money through a complex network of foreign bank accounts and companies.

The Gold: The Inside Story reveals how loopholes in banking practices in the 1980s, the desire to rebuild London’s docklands and a lack of regulation to tackle money laundering, aided the robbers and handlers. These loopholes enabled the transformation of the biggest gold bullion haul in history into cash and in doing so, changed our nation forever.

Speaking in the documentary, Detective Chief Superintendent, Brian Boyce says: “Our task was far greater than just arresting the robbers, we hadn’t even recovered the dust of the gold. We had to work extremely hard, follow the trail and recover as much of the gold as possible.”

BBC Head of History, Simon Young says: "Few robberies are as iconic as Brink’s-Mat or have had such a profound effect on the country. That’s why it’s so fascinating to hear Brian Boyce and his colleagues give such a frank and unvarnished account of the challenges the police faced in attempting to solve such a colossal crime."

The Gold: The Inside Story is a 1 x 60 for BBC One and iPlayer and is made by Bohemia Films. It was commissioned by Jack Bootle, Head of Commissioning, Specialist Factual. The Executive Producer is Min Clough. The Director is Todd Austin. The BBC Commissioning Editor is Simon Young.