He spent considerable time in Munich where he painted Charles Theodore, Elector of Bavaria, among others.
He moved to Switzerland in 1785, and then became the official court painter of Joseph II, Holy Roman Emperor.
In 1786, he travelled to France where he painted under the patronage of Marie Antoinette and Marie-Louise, princesse de Lamballe.
In London in the 1790s, he painted the large The House of Commons, 1793–94, first exhibited in 1795 and now in the National Portrait Gallery.
He painted portraits of leading British politicians such as Charles James Fox and William Wilberforce.