A selection from the eighteen sketches on mahogany veneer of various sizes in the Turner Bequest (Tate Gallery 2302-13, 2676-81). The subjects are all on the Thames or its tributary the Wey; several of the Guildford and Godalming views were identified in 1970 by Mr Christopher Pinsent, including No. 141, formerly thought to show Windsor Castle. The same area, with the exception of Walton Bridges, is covered by drawings in the 'Windsor, Eton' and the ‘Wey, Guildford' sketchbooks, though none of the viewpoints are identical (T.B.XCVII and XCVIII).

The small oil sketches, like these sketchbooks, were dated c.1807 by Finberg (1961, p.137) but, being less closely connected with Turner's exhibited paintings, are more difficult to date precisely. John Gage divides them into three groups. The first, which includes Nos. 135-7, he associates with the Wey and Guildford sketchbook but dates c.1809-10; the second, including No. 138, he dates c.1811-22; and the third, including Nos. 139-41, later still, c.1813 or later, as more accomplished even than the small Devonshire oil sketches of 1813 (see Nos.124-6). The Devonshire sketches, however, are not strictly comparable in either technique or general approach, and again it may be that, as is argued in the case of the large Thames sketches on canvas, the whole group represents a single campaign playing a crucial part in the rapid development of Turner's approach to nature in 1807 and 1808 (see Nos. 143-6).

These sketches were probably done out-of-doors, perhaps from a small boat as the younger Trimmer described, though he talks of Turner using ‘a large canvas' (see Nos. 143-6). In them Turner approaches nearest to what Constable termed 'a natural painter', but, unlike Constable, Turner always seems to have been interested in making a complete pictorial composition even when he came closest to recording a direct experience of nature.