A notorious break-in to a vault in London’s Hatton Garden diamond district netted gold, platinum, jewelry and cash valued at roughly 14 million pounds ($21 million), a prosecutor said Monday.

Prosecutor Philip Evans said the complex caper hatched at a series of Friday night pub sessions was the “largest burglary in English legal history.”

The goods were taken from safety deposit boxes inside the basement vault over the holiday weekend.

Evans said the gang used sophisticated methods and meticulous planning to drill into the wall of the vault before ransacking 73 safe-deposit boxes.

Four men said to be ringleaders have already pleaded guilty to conspiracy to commit burglary. Four others are on trial at Woolwich Crown Court accused of involvement in the theft.

“These four ringleaders and organizers of this conspiracy, although senior in years, brought with them a great deal of experience in planning and executing sophisticated and serious acquisitive crime not dissimilar to this,” Evans said of the four who pleaded guilty. They range in age from 58 to 76.

Prosecutors said much of the planning was done during Friday night sessions at a pub, and that one of the plotters had been using the Internet to search for the best drill for the job for more than two years.

The choice of drill was important because they had to bore a large hole through 20 inches of wall to get into the vault.

The planners took advantage of the long holiday weekend to work unnoticed in the jewelry district in the heart of London.

The four defendants on trial are: Carl Wood, 58; William Lincoln, 60; Jon Harbinson, 42, and Hugh Doyle, 48. They are accused of being part of the conspiracy and helping with the planning and the logistics.

Police said some of the goods and cash have been recovered and some items were shown to the jury.

(AP)