Kneller's output was vast and he made extensive use of assistants. Sitters were required to pose only for a drawing of the face and efficient formulas were worked out for the accessories. He is said sometimes to have accommodated as many as fourteen sitters in a day, and this kind of productivity has inspired some scathing criticism: in 1815 Northcote described ‘the great mass of his works’ as ‘hasty slobbers…scarcely fit to be seen’. It is undeniable that many pictures turned out from his studio were slick and mechanical (and the heavy wigs then fashionable make for great monotony in male portraits), but Kneller was capable of work of much higher quality when he had a sitter to whom he especially responded: outstanding examples are The Chinese Convert (1687, Kensington Palace, London) and Matthew Prior (1700, Trinity College, Cambridge). Many other examples of his work, including the portraits of the Kit-Cat Club, are in the National Portrait Gallery, London.
Ellis Waterhouse writes that ‘he had a wonderfully sharp eye for character, could draw and paint a face with admirable economy, and maintains, even in his inferior work, a certain virility and down-to-earth quality which is refreshing after the languishments of the age of Lely.’ Nevertheless, the influence of his mass-produced work was stultifying. He was the last foreign-born artist to dominate English painting, but it needed a Hogarth and a Reynolds to break through the conventions he had popularized.
Text Source: The Oxford Dictionary of Art and Artists (Oxford University Press)