A metal detectorist recovered the brass artifact from the wreck of the “Ann Francis,” a merchant vessel that sank off southern Wales. Researchers used micro-CT scans to identify the four-letter combination
Ellen Wexler | Writer and Special Projects Editor
November 12, 2026 1:22 p.m.
In 1999, Peter Hughes stumbled upon the brass combination lock on Margam Beach in Wales. It featured four rotating dials, each bearing six letters. The dials turned smoothly, but only one of 1,296 possible combinations would open the device.
The lock was an artifact from the Ann Francis, a merchant ship that sank in 1583. Hundreds of the vessel’s treasures—including compasses, coins and cannonballs—have since surfaced on the beach. But Hughes was particularly intrigued by the lock. He fiddled with the dials for two decades, trying to solve the puzzle.
Now, researchers have used CT scans to reveal the four-letter code: ANCE. When they tested it out, the lock clicked open for the first time in more than four centuries. “For me, it’s like opening the Ark of the Covenant,” Hughes tells BBC Wales’ Meleri Williams. “I’m delighted—truly thrilled.”
The Ann Francis was traveling from Spain to England when a storm swept in on December 28, 1583. The winds blew it off course, and it ultimately wrecked off Margam Beach in southern Wales. According to a parish register, 14 sailors died in December 1583, and these men may have been the Ann Francis’ crew. The record blamed the incident on “the detestable working of an execrable witch.”
As word spread, looters descended upon the beach, prompting legal disputes over the rights to the ship’s treasures. A few months after the wreck, Francis Shaxton, the owner of the Ann Francis, claimed the vessel and recovered some of the items.
For centuries, many more artifacts remained buried beneath the sand. Hughes, a metal detectorist, made his discoveries between 1996 and 2017, aided by dredging and storms that shifted the beach’s sand. He found the combination lock near coin weights and Spanish silver coins—perhaps items that the lock once protected.
“It’s in fantastic condition. It still has its working parts. All of the letters are really clear,” Siân Iles, a senior curator at Museum Wales, says in a video. “I think it’s human nature when you have a code to crack—that’s what you want to do.”
Museum Wales recently acquired Hughes’ trove of artifacts, including the lock. Curators decided to ask researchers at Cardiff University for help identifying the combination. They explained that they had an Elizabethan lock on their hands, but nobody knew how to open it. Would they be able to use micro-CT scanners to peer inside?
David Williams, a biomechanical engineer at Cardiff University, was intrigued. Normally, he studies how humans move, sometimes using micro-CT scanners to see inside 3D objects on a very small scale. He didn’t know whether the scans would reveal anything useful about the artifact. But he had a few history buffs on his team, and they agreed to try.
“Micro-CT scanning allowed us to look inside the lock without damaging it,” Williams says in a statement. “We normally use this technology to study bones and other biological structures, so investigating a 400-year-old padlock was certainly a first for us!”
Trysorau'r Tonnau - Clo yr Ann Francis | Tides of Treasure - The 400 Year Old Lock from a Shipwreck!
When the lock arrived, the researchers conducted an initial scan to determine whether this approach was worth pursuing. When they saw that they could make out letters in the images, they realized the answer might be close at hand.
The team used the scans to determine how the notches on the lock’s dials lined up with the teeth on the key inside them. Unfortunately, the second scan was a bust. The third, however, was much more revealing, suggesting that the long-lost code was ANCE.
“After a couple of days’ work, we were able to be fairly confident that what we had was the correct code,” Alastair Willis, a senior curator at the museum, says in the video. “And then when we took the lock back to the museum, we very carefully tried moving the rings in the right combination.” Right away, he noticed that the four dials felt looser. After conservators cleaned out some of the grit that had accumulated, the lock finally clicked open.
The combination lock is now on display at “Tides of Treasure,” a free exhibition at the National Waterfront Museum in Swansea. The show features other artifacts from the Ann Francis, including a boatswain’s whistle and gold coins dating to Ferdinand and Isabella’s reign.
According to a 16th-century inventory of items recovered from the wreck, at least three chests had been aboard the ship. Their locks had been broken, and no objects were found inside. The researchers wonder whether the combination lock protected one of these chests.
Quick facts: Historic combination locks
- According to Museum Wales, a similar combination lock is currently housed at the British Museum.
- Found in York, England, this early 17th-century lock features one fixed ring and four rotating dials. The word that opens it is MARCI.
“Elizabethan combination locks are known in Britain, but this one is in exceptionally good condition and is associated with a dated wreck, making it a unique find and the code a tantalizing mystery to solve,” Willis says in the statement. “Of course, now we’ve solved it, we are left wondering if the code meant something to its owner.”
In addition to the four letters on the rotating dials, the lock features stationary letters on its outer edges. But how these letters align with ANCE is unclear. Whatever the code’s meaning, Hughes thinks the intricately crafted artifact once protected something dear to the owner’s heart.
“Tides of Treasure” is on view at the National Waterfront Museum in Swansea, Wales, through June 26, 2027.
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Source: Smithsonian Magazine · Ellen Wexler
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