Nicholas Goodison, Ormolu: The Work of Matthew Boulton, London, 1974, p.164 attributes this model of perfume burner on stylistic and constructional grounds. He suggests that they were an early model from the manufactory, circa 1770, and evolved into the celebrated 'Sphinx' vases, so-called for their elaborate sphinx bases. A pair of burners of this model were sold in these Rooms, 25 June 1981, lot 6, from the collection of Avery's Ltd, an engineering company long established on the site originally occupied by Boulton's Manufactory at Soho, Birmingham. It is that pair which are illustrated Goodison, op.cit., pl.95.