CT scans help unlock 400-year-old mystery
4 November 2026
Experts from Amgueddfa Cymru and Cardiff University have used cutting-edge CT scanning technology to unlock a centuries-old combination lock recovered from one of Wales’ most remarkable maritime discoveries.
The brass lock, discovered as part of the Ann Francis treasure hoard, had remained firmly locked since the ship was wrecked off the Welsh coast in 1583. Now, more than 400 years later, researchers have revealed the four-letter code that secured it for centuries: ANCE.
The Ann Francis was caught in a ferocious storm on the evening of 28 December 1583 while returning from Spain and was blown off course before wrecking on Margam Beach, near Port Talbot. The ship's extraordinary cargo remained hidden beneath the sand for centuries, until it was uncovered by metal detectorists before being acquired by Amgueddfa Cymru – Museum Wales.
Working alongside specialists at Cardiff University, museum experts used CT scanning technology to examine the lock's internal mechanism without causing any damage. The scans allowed researchers to identify the correct letter combination and successfully unlock the historic artefact.
Dr David Williams, a research associate based at the Musculoskeletal Biomechanics Research Facility at Cardiff University's School of Engineering, said: “Micro-CT scanning allowed us to look inside the lock without damaging it.”
By creating a detailed 3D image of the internal mechanism, I could see how the notches lined up with the letters and identify the exact combination. 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. I had to wait until later that evening for the museum team to test the combination, so getting the message that we'd cracked it was incredibly satisfying.
“It's not every day you get to solve a 400-year-old mystery!”
It is believed the lock once secured a small chest containing items of significant value. Found near a collection of Spanish silver coins and close to two coin weights recovered from the wreck site, the lock may have protected these objects or secured a chest containing valuable items that have not survived, such as documents or textiles.
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 tantalising mystery to solve. Of course, now we’ve solved it, we are left wondering if the code meant something to its owner.
The majority of the ship's remarkable hoard was discovered by metal detectorist Peter Hughes over a period of 21 years between 1996 and 2017. Peter uncovered the treasure after dredging and storms stripped away layers of sand from Margam Beach, revealing traces of this dazzling sixteenth-century collection.
When I found the lock I was immediately astonished by the incredible workmanship and its astonishing condition. 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. I also remember being left excited at the prospect of finding wonderful things from the treasure chest it once locked.
The combination lock is among a number of artefacts from the Ann Francis hoard currently on display at the National Waterfront Museum in Swansea. Other highlights include rare gold coins dating from the reign of Ferdinand and Isabella of Spain, together with a boatswain's whistle recovered from the wreck.
The acquisition was made possible thanks to support from Welsh Government to bring this important discovery into Wales’s national collection. The display of collections such as the Ann Francis hoard now form part of the National Waterfront Museum's reimagining as a museum of the sea, telling the stories of Wales' rich maritime heritage and its connections with the wider world.
Tides of Treasure is on display at the National Waterfront Museum, Swansea until September 2027.
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