A brass padlock recovered from a ship that sank off Wales in 1583 has finally given up its combination. Researchers used micro-computed tomography to look through the corroded metal without forcing the mechanism, mapped the hidden notches inside its four lettered rings, and reconstructed the code: ANCE.
That answer creates a better mystery instead of ending the story. The lock still has movable dials after more than four centuries underwater, and its maker built 1,296 possible combinations into an object small enough to protect a chest or personal box. Yet nobody knows what “ANCE” meant to the sailor who set it. A name fragment? A private mnemonic? A word whose context went down with the ship? The scan can recover the mechanism, but not the memory behind it.
The Ann Francis went down in a winter storm
The lock came from the wreck of the Ann Francis, a merchant vessel lost near Margam Beach in South Wales on December 28, 1583. Archaeologists have recovered material from the site over many years, including silver coins, lead weights, brass objects and the compact letter-combination lock now held by Amgueddfa Cymru–Museum Wales.
Its four rotating rings each carry six letters. That produces 6 × 6 × 6 × 6, or 1,296, possible settings. Trying every one would be slow under ideal conditions and risky with an archaeological object whose internal parts might be fragile. Even a working-looking dial can hide corrosion, mineral deposits or weakened metal that turns an ordinary puzzle into a conservation problem.
The museum therefore took the lock to Cardiff University’s Advanced High Voltage Engineering Research Centre, where researchers could examine it without cutting it open. Cardiff University’s account of the project describes the technique as micro-CT: a high-resolution form of X-ray imaging that produces a stack of internal slices. Those slices can then be assembled into a three-dimensional model.
A virtual lockpick found the hidden notches
A combination lock does not need to reveal its secret on the outside. What matters is the position of gates or notches inside the rings. When those internal openings line up, another part of the mechanism can move and release the shackle.
The scan made those hidden features visible. Researchers could rotate and inspect the virtual model, trace the internal geometry and work backward from the aligned notches to the letters printed on the dials. That process identified A-N-C-E as the opening sequence. It was a virtual lockpick with an important advantage: the real object did not have to be dismantled to prove how it worked.
After the code had been reconstructed, the physical rings could be set to the corresponding letters. The lock opened. According to the museum, the dials were still capable of turning despite roughly 443 years of burial, recovery and conservation. That surviving movement is almost as striking as the code itself. The object is not merely shaped like a puzzle; much of its original puzzle still functions.
The code is known, but its meaning is not
“ANCE” does not provide an obvious modern answer. It could be part of a longer personal or place name, an abbreviation, a word meaningful to the owner, or simply a memorable arrangement chosen from the available letters. The surviving evidence does not settle the question, and neither the museum nor Cardiff University claims that it does.
That restraint matters because the most tempting version of the story would invent a romantic identity for the code. The real payoff is more concrete: a non-destructive scan can reveal the exact operating logic of a Renaissance security device, separate movable components from solid corrosion, and let conservators test a hypothesis on a digital model before touching the original.
The method also has uses well beyond locks. Archaeological metalwork often reaches museums as a dense, corroded mass in which hinges, fasteners, inscriptions or manufacturing details are invisible. Micro-CT can expose those relationships while leaving the object intact, giving curators a map before they decide whether any physical intervention is justified.
A tiny machine survives its ship
The Ann Francis lock turns a wreck into a human-scale story. Ships carried cargo, but people aboard them also carried valuables, documents and private belongings. Someone selected this unusually sophisticated little machine, learned its setting and expected four lettered rings to keep something safe. The chest or box it guarded has not been identified, and the secret behind “ANCE” may be unrecoverable.
What survived is enough to reconstruct the moment of use: turn four rings, align four hidden notches, and open the lock. Four centuries later, X-rays performed the part its owner would have done from memory.
Additional current reporting and photographs are available from Live Science. Featured image: the brass letter-combination lock from the 1583 Ann Francis wreck, photographed among recovered coins. Credit: Amgueddfa Cymru–Museum Wales. Official museum press image used for editorial coverage; image unchanged.
