Marloes 1 is mounted in a niche in the wall adjacent to where it was discovered. It was found in the base of the wall by workmen in 1984, who were removing part of the wall to enable the construction of public toilets. The findspot is some 100m from Martins Haven, which is a well-established landing place east of Skomer Island, and the stone may have functioned as a way marker or prayer station for travellers.

The stone is a large, water-worn, irregular boulder of quartz diorite. Dimensions are given as 89cm height x 23 < 43 > 30.5cm x 24cm diameter. It is incised with an irregular, double-outline ring-cross with right-angle arm-pits. The carving is thought to date to the 9th-10th century.

Sources include:
Edwards, N. 2007, Corpus of Early Medieval Inscribed Stones and Stone Sculpture in Wales

N Vousden, 09 October 2018