From Page 52 Footnote 335 of Luigi Lanzi’s notebooks edited by Donata Levi:
“Regarding James Byres, a Scottish resident in Rome, Winckelmann mentions his observations on the theater of Taormina (WINCKELMANN 1830-1834, V, 451-452) and also mentions him (about the trochus) as the owner of a gem, a carnelian with Discobolus (ibid., V, 472), which is often mentioned in contemporary antiquarian literature (for example in GUATTANI, I, February 1784, xiii, and in VISCONTI 1782-1807, I , 95, fig. 7 [SIC! actually fig.6] of plate A): Byres “can boast of having in this carving one of the most elegant and beautiful figures, which have ever been carved in gems”.
He is also mentioned in LANZI, Notizie, 56, [another ref.] as the owner of an Etruscan patera. Byres was also preparing a description of the paintings of an Etruscan hypogeum of Tarquinia with copper plates. For information on him see HAWCROFT 1988, passim: he was in Rome from 1756, at first as a painter with interests also in the field of architecture, but since the mid-1760s he was active especially as a merchant and guide. He participated in important affairs, such as the sale of what is now called the Portland vase to Sir W. Hamilton and the Seven Sacraments of Poussin to the Duke of Rutland. He was one of the first visitors to Paestum in 1766 and left Rome in 1790. See also JENKINS SLOAN 1996, 196, for an onyx cameo with bacchanal, which he sold to Lord Fortrose, Seaforth, before 1781. Byres also acted as an agent on the commission for the altarpiece that Mengs was to have made for All Souls College, Oxford (see ROETTGEN 1993, 30). On Byres see also SKINNER 1966, esp. 16-17, FORD 1974 and STAINTON 1974” (a cleaned up machine translation)
More on Byres in Facos 2018