This drawing, though smaller, is very close to three variants of a design proposed by John Mellor for the garden of his house in Bloomsbury Squae in central London; Mellor, a prosperous lawyer, lived there until 1716 when he purchased Erddig in North Wales. The three drawings, which measure 5¾ x 7½in.; 8 x 12 7/8in. and 7¼ x 12½in., belong to the National Trust and are on loan from Erddig to the Clwyd Record Office; they are discussed and illustrated in Gervase Jackson-Stops, An English Arcadia 1600-1990, National Trust exhibition at Hazlitt, Gooden and Fox, 1992, pp. 31-2 nos. 7a, b and c. The three drawings all show a garden seen through a portico with a doorway on the left, but the present drawing, through of a different general design, may have been done for the same project

The idea of using decorative paintings to give an illusion of extra space in a restricted town garden was common in Renaissance Italy, derived as it was from Ancient Roman examples. Thornhill's source was Jacques Rousseau (16 Jan 93), whose 'perspectives' done in France were engraved and who continued to work in London after taking refuge as a Huguenot in 1785. Thornhill was an admirer of Rousseau's works and owned his large design for the orangery at St. Claud (Victoria and Albert Museum)