The Roman mortar was up to 80 mm. thick and given the combined weight of the Roman mortar and the modern plaster backing, it was decided to lift the painting as twelve irregular sections, the size and shape of each section being determined by the major cracks that could be seen in the rear surface of the mortar.
*N.Davey, Britannia, Vol. 3, 1972 (1972), pp. 251-268