Drawn with the sketchbook inverted. As Finberg was the first to observe, this is a study for Windsor Castle from the Thames of circa 1805 (Tate T03870; displayed at Petworth House).1 A sketch loosely related to some of its details of boats and animals is on folio 28 verso of the sketchbook (D05530).
Turner developed this colour study from pencil sketches in the Wey, Guildford sketchbook (Tate D06349–D06350; Turner Bequest XCVIII 132–132a), taken from just below Romney Lock. In doing so, as Hill describes,2 he simplified the foreground, showing an unbroken expanse of river and adding boats, figures and sheep watering, all features that he retained in the picture. Unusually, Turner added the location ‘ISLEWORTH’ to his signature on the picture, which must mean that he painted it there, at Sion (or Syon) Ferry House and working from this study. The brilliant sunshine illuminating the castle must have been a happy exception to the generally poor weather during the early summer of 1805. Butlin and Joll discuss the likely date of the oil and correct the later dating attached by Finberg in the mistaken belief that the sketchbook itself belonged to 1811–12; see Introduction for further discussion.