An Elizabethan padlock has been opened for the first time in more than 400 years after researchers used X-ray imaging techniques to crack its four-letter combination.

The brass lock was part of the Ann Francis treasure hoard, named after the British merchant ship that wrecked during a storm off the coast of Wales in 1583. Researchers believe the lock once secured a chest aboard the ship, before becoming separated from whatever riches it was protecting.