Cf. Howard & Ayers, China for the West, vol. I, op. cit. p. 145 where the authors suggest: " The promenading figures have been variously described as 'Louis XIV and Madame de Maintenon (or Mme de Montespan)', 'General Duff and his wife', and 'A Frisian couple'. Both Beurdeley and Lunsingh Scheurleer are in agreement, however, that the subject is Dutch rather than French. The 'General Duff' of English legend was the Dutch Governor-General Diederik Duiven (1676-1740) who held this post from 1729-31; so that the date is acceptable".