LONDON — Safely inside a car, the men spoke freely—their voices cracked by age and heavy with Cockney accents.

“That is the biggest robbery that could’ve ever been. That will never ’appen again,” one of them bragged. “The biggest robbery in the fucking world, Dan, we was on that cunt.”

These were no idle boasts. A team of four career criminals—with an average age of 69—had just masterminded the biggest jewel heist in British history.

Gold, diamonds, and jewelry worth around $20 million had been methodically removed from an all but impregnable safe in central London.

Terry Perkins, 67 years old and suffering serious ill heath, was convinced the cops would never believe he could have pulled it off. And if detectives did come knocking at his door? “I’ll say, ‘You what, you dopey cunt? I can’t even fucking walk.’”

It took five days for anyone to realize that the basement of the Hatton Garden Safe Deposit in London’s diamond district had been breached in April this year.

When the scale of the theft became clear after a long Easter weekend, Scotland Yard launched one of the biggest investigations in its history.

Men who had served time for some of Britain’s most notorious robberies—including a $38 million gold bullion heist in 1983—were soon considered prime suspects.

Unaware that they were being followed, filmed, and bugged, this over-the-hill mob continued to meet.

“If we get nicked at least we can hold our heads up that we had a last go,” said Daniel Jones, 60.

He had no idea that Perkins’s small blue Citroen and a white Mercedes-Benz owned by Kenny Collins, 75, had been fitted with audio surveillance devices. But the gang wasn’t only bragging about the operation in the relative security of their motor vehicles.

They also continued to meet in the Castle, the same busy North London pub where they had plotted the whole caper.

The same men have been sitting side-by-side in silence through most of their trial, which began at the start of the month, at Woolwich Crown Court.

A lip-reading expert told the court that Perkins could be seen describing—in animated fashion—exactly how they had finally forced their way into the safe on April 4.

The four masterminds, Perkins, Collins, Jones, and Brian Reader, 76, who was known as “The Master,” have pleaded guilty to conspiracy to burgle with intent to steal jewelry.

They will be sentenced at the end of the trial. Four of their alleged co-conspirators have denied all the charges against them.

The plot began at least three years ago when one of the men searched online for the kind of powerful, diamond-tipped drilling equipment that would ultimately be used to penetrate the 20-inch-thick reinforced concrete wall of the safe.

Perkins, who celebrated his 67th birthday during the three-day robbery, is believed to have been responsible for scoping out the elevator that leads down to the safety deposit boxes.

Dressed as an elevator engineer, he was seen two days earlier by staff who believed he was carrying out repairs.

The prosecution says that Jones was another member of the advance surveillance team. One of the alleged gang members told the court that he was a peculiar character, who talked to Rocket, his terrier, as if he were a human.

“Eccentric to extremes,” said Carl Wood, 58, who denies being part of the conspiracy. “Everyone who knew Danny would say he was mad. He would go to bed in his mother’s dressing gown with a fez on.”

Phone records indicate that Jones made at least five trips to Hatton Garden in the months before the heist went down.

When police eventually raided Jones’s home, they found no forensic evidence to link him to the scene of the crime but they did find a walkie-talkie, balaclavas, and a copy of Forensics for Dummies.

Wood admitted in court that he spoke to Jones frequently in the weeks before the raid but claims they were “chit-chatting” and planning walks together—not plotting a brazen diamond heist.

The operation began shortly before 9 p.m. on Thursday, April 2. It was Easter weekend—with public holidays on Friday and Monday—so the Hatton Garden Safety Deposit was due to be closed until the following Tuesday morning.

A red-headed man who remains at large, known only as “Basil,” had hidden inside the building and allegedly allowed his comrades to enter through an emergency exit.

Once inside, the real work began. They knocked out an aerial and cut the telephone line in order to disable the alarm system, jammed the elevator, abseiled down the shaft, cut through a reinforced metal door, and began work on the concrete walls of a safe that was filled with safety deposit boxes.

Up until now, they had shown remarkable knowledge of the inner workings of the building. But once the drills had bored through the 20-inch wall, just as they had seen on industrial YouTube videos they watched, they struck another metal object.

Despite hours of work, they were unable to budge a metal cabinet that had been bolted to the floor and the ceiling. Early the following morning, they left Hatton Garden with nothing more than the tools they had brought for the job.

From the police tapes, it is obvious that this was the moment when the whole plot almost fell apart.

Some of the gang wanted to return with additional tools that would get them through that final line of defense, others believed it was time to call it quits.

One of those who thought it was too dangerous to go back in was Reader—arguably the most experienced criminal among them.

He had served eight years for his part in the Brink’s Mat robbery, in which cash and gold worth $38 million was snatched from a heavily-guarded warehouse near Heathrow Airport.

The three other masterminds later discussed Reader’s decision to pull out as they sat in one of the cars.

Jones said they had pulled off the “biggest tom” robbery in history—in cockney rhyming slang tomfoolery is jewelry. “And if you listen to ‘The Master,’ you walk away,” said Jones, referring to Reader as an “an old ponce.”

“All them months and fucking years he’s put work in, to go; ‘Look, I won’t be here tomorrow.’ ’Cos he’s thought you’ll never get in.”

“I really want to have a go at him but I’ve got to stop myself. Really want to hit him and say, ‘Toughen up, you fucking prick—that’s what you are, you lost all the fucking work, you bottle out at the last minute.’”

Perkins said he wished he had taken a selfie outside the safe—where Reader was supposed to be with him—“I wish I had a photo, Dan, I know you and Basil was inside. I wish I had a photo to show me sat outside all on my own, right, doing what I had to do.”

He said he planned to confront “The Master.” “I am going to say you fucked up every one of them, Brian, you didn’t even look at the front door, you didn’t take the right drill in and this one you fucking walked away from. If we had took any notice of you we would have walked away from it as well.”

The prosecution claims that Carl Wood also refused to return on the second night. In the same conversation in the car, Collins said: “Carl’s different. His arsehole went.”

The rest of the men are accused of returning to the scene of the crime for a second night on the Saturday.

This time they were equipped with a powerful hydraulic jack that could punch the metal cabinets out of the way.

Once the path had been cleared, at least two men crawled into the safe through the drill hole, which measured 10 inches by 17 inches.

Smashing into the safety deposit boxes themselves was relatively easy. The precious gems, watches, and gold was passed through the drill hole and loaded into large trash cans which had been calmly wheeled into the building.

It was a lot harder to move them once they were so heavily-laden. CCTV cameras caught one of the gang leaning on the receptacle as he tried to catch his breath.

By 6:45 a.m. on Easter Sunday, the gang members and their haul were safely ensconced in a white van and being driven slowly away from the scene.

The prosecution claims that the getaway driver was William “Billy the Fish” Lincoln, 60.

Lincoln says he couldn’t have been idling outside Hatton Garden Safe Deposit in a white Ford Transit van in the early hours of the morning because he was down in the East End of London at the Billingsgate fish market with his mate “Jimmy Two Baths.”

Lincoln denies all of the charges against him, as does Jon Harbinson, a taxi driver allegedly referred to as “The Taxi Driver” on the police tapes.

Prosecutors claim that a raid on Harbinson’s house uncovered a copy of the true-crime thriller Killer by Charlie Seiga.

A section that described a theft using high-powered drills was marked with a piece of card.

“It was bookmarked on a page that is exactly what took place in Hatton Garden,” said Philip Stott, the prosecutor.

“I had no knowledge of what happened in Hatton Garden,” Harbinson replied. He claimed that he had never seen the book, although he was forced to agree that the makeshift bookmark appeared to be a piece of gray card, of the type found at the back of a book of taxi receipts.

Flying Squad detectives raided the alleged gangsters on the day that they met in the car park outside the Old Wheatsheaf pub in Enfield, where police say they watched the men divide up some of the loot.

Much of the booty had already been hidden.

When Reader confessed to his involvement in the crime, he led police officers to a cemetery in the suburbs of London where he had buried jewels, cash, and rings in a relative’s plot.

He insisted that was all he had received from the heist, but officers found a far bigger haul at the grave of his father-in-law.

The trial will continue on Jan. 4, but police say “Basil” is still at-large.

About a third of the diamonds and gold that was contained in the 73 safety deposit boxes has now been seized by detectives—that would suggest that somewhere out there remains more than $10 million worth of buried treasure.