Cloth Seal, Norwich, Castle, Portcullis

Cloth Seal, Norwich, Castle, Portcullis, Image & Found by Simon Bourne.
Found on Thames Foreshore, 21mm.

3 X 2 portcullis // castle with lion passant below, C (N) to sides, inscription around?

The arms of Norfolk omit the lion, therefore this is a Norwich seal.

See p.195 & Fig.48, Provenanced Leaden Cloth Seals by Geoffrey Egan, Sub-Department of Medieval Archaeology, University College, University of London. submitted for the degree of Doctor of Philosophy, "Medium-sized seals with a portcullis: "crown over portcullis [2 vertical and 3 horizontal squares] C(IVIT)ATISXNORWIC around // castle, lion passant below [arms of Norwich], CN to sides, + CI(VITAT)IS x NORWICI around ... Presumably the initials to the sides of the arms echo the 'civitatis Norwici' legends."