Louis-Michel van Loo

When the philosopher Denis Diderot sat for Louis-Michel van Loo in 1767, he did not much like the result. Diderot, who reviewed the Paris Salon that year, wrote that the picture was charming but did not resemble him: too dressed up, too coquettish, a flattering stranger his own grandchildren would fail to recognise. The portrait hangs in the Louvre today, and it is probably why most people still know van Loo's name.

He came from a dynasty of painters. Trained by his father Jean-Baptiste, he spent some 17 years as court painter to Philip V of Spain in Madrid, where he helped found the royal academy, before returning to Paris to paint Louis XV and to run the French academy's school for promising young artists.

Van Loo spent his career on kings and courtiers in the polished Rococo manner of the French court, which makes the Diderot, a writer at his cluttered desk with pen in hand, unusual among his surviving works.