Constable may well be a forerunner of the later French avant garde, as Jonathan Jones suggests (The volcanic, uncontrollable visions of a master reborn – Late Constable review, 26 October). This is also down to his use of broken colour – applying dabs of paint without mixing them – as explained in The World Through Blunted Sight by Patrick Trevor-Roper (1970). He argued that this – along with Constable overloading his green with red, and the use of his white flecks – attracted the attention of Corot and many subsequent French painters, and could have been one foundation for the broken colour in many French impressionist paintings. He also thought that this was evidence of Constable being somewhat red-green colour blind. So, impressionism could have been the result of a painter with a visual disability, and an English one too.