The subject is continued (with other details) on folio 44 of the sketchbook (D07038; Turner Bequest CV 40). See Introduction to the sketchbook for this subject and for related plans in the mid 1820s for a series of London subjects, including the Custom House. As in many drawings in the book, the composition is similar to The Custom House (Vancouver Art Gallery),1 engraved by J.C. Allen, 1827; here, it is extended further upstream.
Andrew Wilton, The Life and Work of J.M.W. Turner, Fribourg 1979, pp.358–9, no.516.