Orton published an influential essay in 1991 in the
Oxford Art Journal that argued that
Harold Rosenberg, the critic who coined the term "
Action painting", developed the concept as a result of his commitment to
Marxism rather than to the photographs of
Jackson Pollock in action. According to art critic Stephen Moonie, Orton's essay was one of the first attempts to define the term, offering a "political reading" which, "as Orton shows with great diligence", was a continued effort in Rosenberg's career. With
Griselda Pollock he wrote
Avant-Gardes and Partisans Reviewed and
Vincent van Gogh: Artist of his Time. A social historian of art, he is influenced by
Marxist theory. His 1994 book
Figuring Jasper Johns investigated the relationship between
Jasper Johns and
Frank O'Hara. Orton is also one of the editors of a collection on the
Ruthwell and
Bewcastle crosses, and with
Catherine Karkov edited an important collection on Anglo-Saxon stone sculpture; he contributed one essay, and three other essays are responses to his. ==Books published==