Nigel Cawthorne - The Great Diamond Heist--The Incredible True Story of the Hatton Garden Diamond Geezers

I walked past the Hatton Garden Safe Deposit Company on that Easter Sunday just a few hours after the diamond heist gang had scarpered with their loot. I was on my way to have lunch with my elderly mother, who lives out in Surrey. To catch the train there, I walked from my flat in Bloomsbury to Farringdon Station. My route took me, unsuspecting, down Hatton Garden. It was unusually quiet. Seventy per cent of the businesses were Jewish. The day before had been Passover and their shops were closed for the holiday weekend.

That particular Sunday I would certainly not have taken my other possible route that was to take a bus from Southampton Row to Waterloo Station to catch the train there. A few days before, there had been a mysterious underground fire in Kingsway. The street was closed off and the buses had been diverted.

As I strolled through the heart of Londons jewellery district on the morning of 5 April 2015, I cannot say I noticed anything suspicious, though just a metre or so beneath my feet there was a ransacked strongroom and a hole in the wall of a vault, whose shape has since become iconic.

The police famously had not noticed anything suspicious either. Two days earlier, the burglar alarm had gone off in the building. The police were informed, but decided not to investigate. They were, after all, busy directing traffic away from the scene of the fire in Kingsway, half a mile away.

The buildings security guard, Kelvin Stockwell, was roused from his bed when the alarm went off in the early hours of Good Friday, 3 April. Arriving at the building, he took a look around but saw nothing amiss. Though the crooks were hard at work below street level, the basement appeared secure, so Kelvin went home.

Local residents were well accustomed to the sound of drilling and vibration. Crossrail were tunnelling from Holborn Station, near the Kingsway fire, under Hatton Garden to Farringdon Station, a hundred yards further on. The company had sent out letters warning locals about the tunnelling and the demolition work needed to make way for the new ticket hall at Farringdon so no one thought anything of it and the burglary was not reported until Hatton Garden opened for business again on the Tuesday morning. By then, the burglars had been home, basking in their good fortune, for two days.

Scotland Yard issued a statement saying: At approximately 08.10 hours today, Tuesday 7 April, police were called to a report of a burglary at a safety deposit business at Hatton Garden, EC1. The Flying Squad is investigating and detectives are currently at the scene. It appears that heavy cutting equipment has been used to get into a vault at the address, and a number of safety deposit boxes have been broken into.

At the time the size of the heist was still unclear.

We are still trying to establish exactly what has been stolen and who the losers are, said one of the police at the scene. It was a chaos inside.

Insurers said it would be some time before the true extent of the losses was known but no one had been hurt. The police appeared clueless. It seemed like the perfect heist.

No dealer would be foolish to leave all their stock in one place, a London diamond dealer observed, but even if they left a fraction of the uncut and semi-polished diamonds and other stones in a single box, the value could easily run into millions for one box alone.

Local jeweller, Norman Bean, who had stored around 35,000 of jewellery there, upbraided Kelvin Stockwell.

I came down and spoke to a security guard, he recalled. He said he came on Friday, the alarm was going off. He went downstairs, looked through the door, through the windows, and couldnt see anything and came out again. That was it.

I said, Well, why didnt you open up and have a look in? He told me he doesnt get paid enough. They could have been there all weekend. Who knows? Its a disgrace. Its like something out of a film. I cant believe it could happen.

Defending his actions later, Kelvin Stockwell said: You dont know what youre going to walk into. You cant take that chance. Because I could have walked in, I dont know what would have happened to me. I could have been clumped across the head or got tied up, whatever. Thats why the policy was you dont go in on your own. You wait and hopefully if the police turn up, you can go in with them.

But, of course, they didnt.

It was then discovered that the same high-security depository had been raided thirteen years earlier when a thief posing as a customer emptied a number of safe deposit boxes. This time the haul was worth some 500,000. The Hatton Garden Safe Deposit Company had also been robbed in 1975, when armed robbers burst in, threatened staff and made off with an estimated 1.5 million in gems, cash and other valuables.

In the first reports of the Hatton Garden heist, it was thought that the haul might beat the estimated 60 million stolen from the Knightsbridge Security Deposit Centre in July 1987, where Italian armed robber Valerio Viccei requested to rent a deposit box. He and an accomplice then pulled guns, subdued the staff, broke into the boxes and made off. While other gang members were soon rounded up, Viccei fled the UK, though the fact that he had left behind one bloody fingerprint assured the Metropolitan Police that he was the ringleader.

With safety deposit box heists, it is impossible to get an accurate figure for the haul. No one but the depositor knows what is in the box. Sometimes they will contain valuables, dubiously obtained or being kept hidden from the authorities, that the owner will not admit to. Then there are other owners who might seize the opportunity to inflate the value of the contents of their box to make a dodgy insurance claim.

The Knightsbridge heist certainly rivalled the burglary of the Banco Central of Fortaleza in Brazil in 2005, where thieves spent three months tunnelling under two city blocks, then through three-and-a-half feet of reinforced concrete to steal some US$72 million in currency. Even this was small beer compared with the most lucrative bank robbery in history, where former Iraqi dictator Saddam Husseins son Qusay made off with $920 million from the Central Bank of Iraq in 2003.

But when it came to safety deposit box heists, it was thought that Hatton Garden would top the polls. Former Flying Squad chief Roy Ramm said: I would not be surprised, given where this one is, in Hatton Garden, if 200 million is around the amount stolen.

But we may never know.

The amount of money and the goods that are taken is never fully revealed, he added, and theres a good chance that not everybody would declare.

However, he told BBC Radio Fours Today programme: Theres a sort of old-fashioned audacity about it.