Working Drawings at Binham Priory?

Volunteers for the Norfolk Medieval Graffiti Survey have found large drawings of arcs and lines marked by dividers inscribed on a wall of Binham Priory. Matthew Champion, project director of the NMGS, suggests that these are working drawings, perhaps of the building's west front. Binham priory's mid-thirteenth century facade was among the first in England to incorporate bar tracery.

Eastern Daily Press article
BBC News article with video