This subject was correctly identified as Battle Abbey gatehouse by Edward Croft-Murray in pencil annotations to a copy of Finberg now in Tate’s Library. The gatehouse is seen from just inside the walls of the abbey. Another view of it is on folio 50 of the sketchbook (D05667). For Battle Abbey in this book see notes to folio 45 (D05662).
There are splashes of ink or grey wash on this leaf.