This drawing, executed on a small scale, relates to the group of works in the British Museum (TB CCCLXXIX), discussed in detail in the article by A. Wilton, 'The 'Monro School' Question: Some Answers', Turner Studies, vol. 4, no. 2, pp. 11-14.
Andrew Wilton, loc.cit. states that both Turner and Girtin seem to have been employed in making a long series of small watercolours in about 1797, perhaps for a publication in a projected topographical work for Dr Thomas Monro, the more likely since very many of them were included in the Monro sale at Christie's, 1833.