Over the Easter holiday in 2015, millions of dollars worth of cash, gems and jewelry were stolen from a facility where London jewelers stored their wares. The audacious theft — which involved descending through an elevator shaft and drilling through concrete and metal walls — seized the attention of the world.

Now three men have been found guilty in connection with the case. Four other men — the ringleaders, by many accounts — pleaded guilty last year.

One suspect, "Basil," is still on the lam.

The BBC calls the group "The Dad's Army," referencing a classic British sit-com about elderly men, because the men involved are:

Brian Reader, known as The Master, 76Danny Jones, 60John (Kenny) Collins, 75Terry Perkins, 67William Lincoln, aka Billy the Fish, 60Hugh Doyle, 48Carl Wood, 58"Basil", unknown

Reader, Jones, Collins and Perkins, all retirees, had previously pleaded guilty to conspiracy to burgle.

On Thursday, Lincoln, Doyle and Wood were found guilty of assisting in the heist.

The head of the Flying Squad — the elite branch of the Metropolitan Police that investigates armed robbery — called the crime "an audacious, brazen burglary that was some three years in the planning," and said police have so far restored over £3.7 million ($5.3 million) in gold and jewelry.

The man referred to as "Basil" is still missing. He's believed to be key to the break-in, as reporter Martin Evans explained to NPR's Scott Simon in December. He literally opened the door for the gang:

"This robbery took place over Easter weekend in April, which is a long bank holiday weekend — a five-day holiday in the UK. All the businesses would've closed for four or five days. And around 8:30 p.m., the alleged gang arrived in a van and started loading equipment in the street."Now to any passerby, they would've perhaps looked like workmen carrying out some sort of repair work. They gain entry to the fire escape, which is opened for them by an unknown member of the gang, possibly the only member of the gang who hasn't been caught.

The men climbed down a lift shaft with a heavy industrial drill and drilled through a thick concrete wall. But then, Evans says, they ran into a metal cabinet they couldn't shift.

"Now, less tenacious people might decide to call it a day, but this gang didn't," he told Scott. "So they traveled to another part of London where they'd buy another piece of equipment and they return ... once again gain entry through the fire escape, and have a second go."

That time, it worked.

As they were pulling off their caper, the men were "on many levels your typical group of pensioners," the BBC writes:

"Brian Reader used a free bus pass. Kenny Collins was the lookout who frustrated others in the gang who said he fell asleep during the raid. Terry Perkins was a diabetic who took all his medication into the vault with him in case he needed it."

As for how they got caught? There was CCTV footage, for one thing. But the police had a lucky break: the men involved were experienced thieves, but not great at secret-keeping, the New York Times reports. Police "overheard the men boasting about the heist in Cockney rhyming slang," the newspaper writes:

"Officers also eavesdropped on the men as they discussed how to divide and sell the stolen goods at the Castle pub in Islington, a north London neighborhood. After a few pints of beer, the men became more and more boastful, unaware they were being observed and recorded, the police said."

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