Curious Monumental Brass

I have a rubbing of a Brass, presenting some peculiarities which have hitherto puzzled me, but which probably some of your more experienced correspondents can clear up. The Brass, from which the rubbing is taken (and which was formerly in the Abbey church of St. Albans, but when I saw it was detached and lying at the Rectory), is broken off a little below the waist; it represents an abbot, or bishop, clad in an ornamented chasuble, tunic, stole, and alb, with a maniple and pastoral staff. So far all is plain; but at the back (i.e. on the surface hidden when the Brass lay upon the floor) is eng…