Shipwreck padlock code cracked after CT scan solves 400-year-old mystery

Experts have used cutting-edge technology to open a centuries-old combination lock from one of the most “remarkable” shipwrecks found in the UK.

The Ann Francis vessel was caught in a ferocious storm and blown off course on 28 December 1583 while returning from Spain. Francis Shaxton of Kings Lynn, the ship’s owner, had sent a valuable cargo of grain to Spain and had now lost both ship and payment.

The ship was wrecked on Margam beach off the coast of Wales and the majority of its incredible hoard was uncovered by metal detectorist Peter Hughes over a 21-year period of 21 years.

Among the treasures was a 400-year-old brass combination lock that is believed to have 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.

Researchers from Amgueddfa Cymru and Cardiff University used CT scanning technology to examine the lock's internal mechanism without causing any damage.

These scans allowed researchers to identify the correct letter combination – ANCE – and successfully unlock the historic artefact.

“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,” said Dr David Williams, a research associate based at the Musculoskeletal Biomechanics Research Facility at Cardiff University's School of Engineering.

“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.”

Mr Hughs said he was “immediately astonied” by the workmanship and the condition of the lock when 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. “I also remember being left excited at the prospect of finding wonderful things from the treasure chest it once locked.”

The combination lock, alongside a number of artefacts from the Ann Francis hoard, is currently on display at the National Waterfront Museum in Swansea until September 2027.