CT scans crack the four-letter code of a lock from a ship wrecked off Wales in 1583

A brass combination lock that stayed shut for more than 400 years has given up its code, Phys.org reported on 4 November: the four letters are ANCE. Experts from Amgueddfa Cymru (Museum Wales) and Cardiff University read it with micro-CT scans, which look inside an object without opening it.

A treasure ship lost off Port Talbot

The lock comes from the Ann Francis, which was wrecked on Margam Beach, near Port Talbot, in a storm on 28 December 1583 while returning from Spain. Metal detectorist Peter Hughes found most of the hoard between 1996 and 2017, after dredging and storms stripped sand from the beach. He found the lock near Spanish silver coins and two coin weights, and its ring dials still turned easily. The museum's exhibition page had described the secret word as uncracked by all who tried.

Looking inside instead of forcing it

“Micro-CT scanning allowed us to look inside the lock without damaging it.” — Dr. David Williams, Musculoskeletal Biomechanics Research Facility, Cardiff University

The scanning, led by Williams, showed the internal mechanism and so the letters that open it. The lock probably secured a small chest, perhaps holding valuables or perishable items such as documents or textiles; the chest has not survived. Alastair Willis, senior curator for numismatics and the Welsh economy at Amgueddfa Cymru, said Elizabethan combination locks are known in Britain, but this one is in unusually good condition and is linked to a dated wreck.

What ANCE meant is still unknown

The code raises a new question. Nobody knows whether the letters meant anything to the lock's owner, and the report offers no explanation.

The lock is on show in the exhibition Tides of Treasure at the National Waterfront Museum in Swansea, alongside gold coins from the reign of Ferdinand and Isabella of Spain and a boatswain's whistle. Admission to the exhibition is free, according to the museum.