During drainage excavations carried out between 2001 and 2003, archaeologists recovered the slabs from the riverbed, where they had been repurposed as rubble fill to form a protective apron around the piers of a late medieval bridge. The working theory is that they were deliberately cleared from a nearby graveyard, packed in with other stone, and submerged, their inscriptions and carved surfaces pressed into the mud.

One fragment among the thirteen is particularly telling. The piece, a limestone slab measuring roughly half a metre in length and just under a third of a metre wide, represents only the upper portion of what was once a complete graveslab. It has been recut at some point in its life, its upper surface lightly punch dressed, a technique used to create a roughened texture on stone, and it carries traces of light grey gritty mortar on its plain reverse face, evidence of its time built into the bridge structure. On its decorated face, a plain centred incised cross was carved, with trefoil terminals, the three-lobed leaf shapes that finish each arm of the cross. Only one of those terminals survives. Stylistically, the carving places the slab in the thirteenth or fourteenth century. The graveyard it came from was almost certainly associated with either St Mary's parish church, about a hundred metres to the west of where the bridge stood, or St John's Priory, roughly two hundred metres to the north-east. Both were active religious sites during the medieval period, and both would have held burials. Whoever commissioned this slab, and whoever it once marked, is entirely unknown.

The fragment's current whereabouts are unrecorded. It was recovered during the excavation, catalogued, and has since dropped from the accessible record. The bridge it was taken from lies immediately north of the present John's Bridge, its medieval fabric long since altered or replaced.