The artist is Rokotov
Vorontsov Ivan Illarionovich (1719-1786) – Count, Chancellor’s brother M. And. Vorontsova and r. And. Vorontsova; Uncle President of the Russian Academy of Sciences Princess E. R. Dashkova. The chamber-junker of Grand Duke Peter Fedorovich, since 1761 General-Rodchik. Senator (1768), a real chamberlain, president of the estate collegium in Moscow. Was married to m.AND. Volynskaya – daughter of the famous office of Artemy Volynsky.
Depicted with the orders of the White Eagle (tape) and St. Anna (Cross).
Varyled copy executed. G. Levitsky (late 1780s-early 1790s),-Pavlovsky Palace Museum (GMZ “Pavlovsk”).