--- title: "CT scans crack the four-letter code of a padlock locked since a 1583 shipwreck in Wales" url: https://badiyaa.com/ann-francis-shipwreck-padlock-code-ance/ published: 2026-11-05T11:11:00+00:00 modified: 2026-11-05T11:11:00+00:00 section: History publisher: Badiyaa --- # CT scans crack the four-letter code of a padlock locked since a 1583 shipwreck in Wales The word is ANCE. A micro-CT scan read the notches inside the brass lock from the Ann Francis, wrecked at Margam near Port Talbot, without forcing it open. The password was ANCE. For more than four centuries, a small brass padlock pulled from the sands of Margam Beach in south Wales kept its four-letter secret, and this week a team in Cardiff read it straight out of the metal with an X-ray scanner built for studying bones. The lock came from the Ann Francis, an English merchant ship that a storm drove ashore near Port Talbot on the evening of December 28, 1583. Amgueddfa Cymru, the national museum of Wales, and [Cardiff University announced the result on November 4](https://www.cardiff.ac.uk/news/view/3118948-ct-scans-help-unlock-400-year-old-mystery), more than 440 years after the wreck. ## How a scanner read a lock nobody could open Nobody forced the shackle. Dr David Williams, a research associate in the university’s School of Engineering, put the padlock through a micro-CT scanner, which builds a 3D picture of an object’s insides from hundreds of X-ray slices. “Micro-CT scanning allowed us to look inside the lock without damaging it,” Williams said. Inside, each lettered ring has a notch. When all four notches line up, the locking bar can slide free. By seeing which letter sat above each notch, he could read the combination without turning a thing. He then had to wait. “I had to wait until later that evening for the museum team to test the combination,” he said, “so getting the message that we’d cracked it was incredibly satisfying.” His lab normally scans bones and other biological structures, so a 400-year-old padlock was a first. ## The math behind a 16th-century password The museum’s catalog entry gives an unusually precise picture of the device. It is a little over 3 centimeters tall, weighs 28.5 grams, and carries 34 engraved capital letters: 10 around the two fixed end plates and 24 spread across four rotating rings. That works out to six letters per ring. Picking one letter on each of four rings gives 6 x 6 x 6 x 6 = 1,296 possible settings. A patient owner who lost the word could, in principle, have tried them all; at five seconds a try, that is about 108 minutes of fiddling. The catalog’s letter list for the rings does contain an A, an N, a C and an E, one on each ring. Locks of this kind, sometimes called Nuremberg locks, are not unknown in Britain. The museum notes that one found on the Suffolk coast is frozen shut reading OXEN, and an example in the British Museum’s collection opens with the word MARCI. Real words were a natural choice for owners who had to remember them. ## Timeline: from storm to scan - **October 1583:** The Ann Francis sails from King’s Lynn, Norfolk, for the Iberian Peninsula with wheat, according to the museum’s history of the ship. - **December 28, 1583:** Heading home with payment from Spain, the ship is driven onto the Glamorgan shore. Under today’s Gregorian calendar, that date is January 7, 1584. - **1583 to 1584:** Local lords fight over the wreck in the Star Chamber court. One inventory lists three chests “with their locks broken,” along with cloves, marmalade and Spanish silver. - **1970s to 1990s:** Compasses, coins and a bosun’s whistle turn up on the beach, and researchers tie them to the Ann Francis. - **1996 to 2017:** Detectorist Peter Hughes recovers most of the hoard, including about 870 gold and silver coins, over 21 years. - **November 4, 2026:** The CT result and the word ANCE are made public. ## What was it guarding? The lock turned up near Spanish silver coins and two coin weights, so the museum thinks it fastened a small chest of valuables. That chest may have held those coins, or things that rotted away long ago, such as papers or cloth. Hughes still remembers the moment he found it. “When I moved the ring dials of the combination they turned with ease after over 400 years beneath the sands and I was left in disbelief,” he said. The ship’s owner, Francis Shaxton, came from a King’s Lynn merchant family the museum calls notorious smugglers, and he had claimed the ship was bound for Hartlepool rather than Spain. Whether the owner of the padlock was Shaxton, a crewman or a passenger is not recorded. And ANCE is not an English word. Alastair Willis, senior curator for numismatics and the Welsh economy at the museum, said the find is unique because it is so well preserved and tied to a dated wreck. “Of course, now we’ve solved it, we are left wondering if the code meant something to its owner,” he said. The lock is on show with gold coins of Ferdinand and Isabella and the ship’s boatswain’s whistle in the Tides of Treasure display at the National Waterfront Museum in Swansea, catalog number 2025.17H/2.6. ## Further reading - [Cardiff University: CT scans help unlock 400-year-old mystery](https://www.cardiff.ac.uk/news/view/3118948-ct-scans-help-unlock-400-year-old-mystery) *Image: Gareth James, CC BY-SA 2.0 via Wikimedia Commons* *This article was produced with AI assistance and reviewed by our Editorial Desk. [How we work](https://badiyaa.com/editorial-policy/).*