There are two such marks on the Terrace edging stones, but they are quite roughly made, and I suspect they mean some reference datum at the time. The one on Market house is quite definitely a mason s mark. This one is a precise cut, the arms are wedges; it may be some ordnance mark (I have not noticed this one) - The Admiralty used marks such as these, as well as the Ordnance Survey.
This appears just above the slope near the bottom end of MJS just opposite the wharfside entrance....and is outside the Claredon shop (look out for my one which will be uploaded soon!)
