Mosnier studied at the Academy St Luc, Paris, before becoming official painter to Marie Antoinette in 1776. His handling of paint when describing fabric earned him the moniker ‘Roslin of the min’. In 1788 he became a full member of the Royal Academy but left France shortly afterwards during the Revolution. He is noted as moving to Hamburg at this point but certainly arrived in London some time around 1790, as he began to exhibit at the Royal Academy from 1791. He adapted well to British taste and gained some important commissions. Moving from London to Germany, Mosnier gained further important patrons, including Louis Ferdinand of Prussia (1772-1806) (Louvre, Paris). Arguably, his most important move came in 1801, when he travelled to St Petersburg. His arrival came at a most auspicious time, as the French artist Elisabeth Vigée-Lebrun was planning her exit from the city. Mosnier was accepted into the St Petersburg Academy, becoming professor there in 1806. He died in Russia in 1808.
Painted circa 1785, this portrait was painted during Mosnier’s last years in Paris, the city of his birth. A very similar portrait is in the Tansey Collection, Celle, Germany, dated 1784. The present work, signed by the artist, displays his signature bold handling of gouache paint. His artistic confidence, both in watercolour and oil, led Schidlof to call him ‘one of the best French miniaturists of his period.’