Scientists have successfully deciphered the combination of a 400-year-old padlock recovered from a shipwreck, solving a centuries-old maritime puzzle. The breakthrough was achieved using advanced micro-computed tomography (CT) scanning, a technique typically employed in medical imaging.
The lock belonged to the Ann Francis, a vessel that sank off the coast of South Wales in December 1583 during a severe storm while en route from Spain. Its cargo remained undiscovered on Morfa Beach in Port Talbot until the late 1990s, when it was found by metal detectorist Peter Hughes. The recovered hoard included gold and silver coins, personal items, and the now-deciphered brass padlock.
Hughes spent approximately 20 years attempting to unlock the padlock without success, comparing the challenge to deciphering the Da Vinci Code. A collaborative effort between Museum Wales and Cardiff University eventually cracked the four-letter password: ANCE.
Researchers utilized micro-CT scanning to create a detailed 3D image of the lock's internal mechanism. This allowed them to observe how the notches aligned with the letters on the four rotating rings, each featuring six letters, revealing the correct combination out of 1,296 possibilities. The lock also featured non-moving letters on its ends, which scientists believe may have served as decoys.
Dr. David Williams, a research associate at Cardiff University’s School of Engineering, expressed his astonishment at the success, stating, "I was blown away that we actually cracked it." He noted that the CT scanning technology was not originally designed for this purpose but proved effective for the challenge.
The padlock itself is considered a significant find, described as being in "wonderful condition" and still functional as it would have been centuries ago. Its close proximity to the Ann Francis wreck and other recovered artifacts allows for precise dating.
While the exact contents the padlock was protecting remain unknown, researchers speculate it may have guarded a captain's chest containing Spanish silver, valuable textiles, or important maritime documents.
The discovered padlock is now on public display at the National Waterfront Museum in Swansea.