Perhaps a right-hand page of the sketchbook; no stitch holes are visible but there are traces of dirt along the right margin.
For Pevensey Castle in this sketchbook see notes to D10326
; Turner Bequest CXXXVIII 7, and for possibly earlier drawings, the Herstmonceux and Pevensey
sketchbook (for example Tate D05630
; Turner Bequest XCI 13).