BNPS / PETER CORNS Katie Patterson and George Edmunds celebrate after the remarkable detectorist recovers her ring

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George Edmunds recovered Katie Patterson’s diamond ring, which had passed through three generations of her family, six days after it was lost in five feet of water off a beach in Mallorca. “The look on Katie’s face when she saw it was a picture. There was lots of joyful sobbing and hugging,” he says. “It was quite emotional.” But yesterday it emerged that Weymouth-based Edmunds, 75, is far more than a hobby diver who recovers trinkets for a living. In an exclusive interview with the Daily Express he claims to have cracked a world-famous cipher that has defeated the efforts of some of the country’s finest minds for more than 250 years.

The Shugborough Inscription is a sequence of letters carved into the base of a sculpted relief called the Shepherd’s Monument in the grounds of Shugborough Manor, Staffordshire, the ancestral home of the earls of Lichfield. Charles Darwin, Charles Dickens and even veterans of Bletchley Park, the wartime decryption operation that cracked the Nazis’ Enigma code, have all tried to make sense of the cipher over the years.

PETER CORNS The ring belonged to Katie's grandmother

Now Edmunds says he has succeeded where they failed. In a new book being launched at the Institute of Directors on Pall Mall next week he will reveal how. His interest in the cipher began when he looked into a secret expedition mounted by Admiral Lord George Anson in the mid- 18th century to recover a cache of hidden treasure.

I’ve always been a wreck diver and underwater detecting is an extension of it Detectorist George Edmunds

Anson is the family name of the Lichfields and the admiral was born at Shugborough. While the estate passed to George’s older bother Thomas, the younger man – who made a fortune out of Spanish plunder – is believed to have paid for the creation of the Shepherd’s Monument. Edmunds’ research led him to believe that its cipher was a clue to the location of Anson’s cache. By the time he reached this conclusion he had a pretty good idea of where the treasure had been left and via a process of reverse engineering, the study of various ciphers used by secret societies of the time and the work of an author called William Mann he arrived at his solution. “I was successful because I had a good idea what the answer was likely to be,” he writes.

“With clues from Mr Mann’s book, research and ‘reverse engineering’ I was able to achieve it.” So where did so many eminent authorities go wrong in their quest to solve the inscription? “Most people had been looking at the romantic poetic angle, thinking it was something Greek or Latin, totally forgetting that Lord Anson was a naval man,” he says. “The cipher gives the latitude and longitude of an island. It is a tiny little island in the Pacific Ocean and I’m 90 per cent sure the treasure is still there.” Don’t be surprised if Edmunds visits this treasure island for a TV documentary sometime soon. His book has the imprimatur of the present Earl of Lichfield. The foreword to the 550-page tome is written by Tom Anson, 37, who grew up steeped in the lore of his swashbuckling forebear.

PETER CORNS As well as finding lost diamonds Mr Edmunds claims to have cracked the Shugborough Inscription

He writes: “Centuries have now passed, the questions remain unanswered and still no hidden treasure found. This may all be about to change with the publication of this book which blows the lid off previous theories. “George Edmunds has produced a beguiling book that will change the course of history… Besides telling my ancestor’s secret history this is a thrilling and fascinating book of real events, real people and real treasure mysteries explained and solved. Forget Treasure Island, this is the real thing!” Edmunds’ interest in lost treasure arose out of his love of diving, which he first took up as a teenager in the late 1950s in his hometown of Newport, Gwent. “I’ve always been a wreck diver and underwater detecting is an extension of it,” he says. “I remember diving off the Isle of Wight on the wreck of a Dutch East Indiaman 30 years ago, we could detect coins. The technology was pretty good even then.” To this day he uses a metal detector called a Surf II from Invernessbased White’s Electronics that he bought more than 20 years ago for £450.

“You sweep the detector with the coil just slightly brushing the ground and do a search pattern sweeping in front of you back and forth,” he says. “It is exactly the same underwater, just that you’re working in water instead of air. “The equipment that I use has a discrimination feature on it, which means you can differentiate between valuables and junk like bits of iron, nails and so on. You can set the machine so it only responds to highly conductive metals such as gold, silver, and copper.” Until recently Edmunds had a display case containing no fewer than 360 rings, as well as necklaces, bangles and medallions, that he had picked up over the years. When he sold the contents two years ago they fetched £3,500. He says: “A lot of wedding rings are 22 carat and, if they’re quite heavy, you’re talking hundreds of pounds for one ring.”

GETTY The code is 250 years old and has defeated many of the country's finest minds