Every so often, John Deakin, jug-eared chronicler of Soho and hanger-on at the Colony Rooms, is breathlessly rediscovered as the unknown giant behind Bacon and the forgotten man from Soho’s  generation of genius. All that is so much tosh: Deakin is no genius and he has not been forgotten. In fact, he can never be forgotten, most importantly because Bacon commissioned photographs from Deakin that he used to make his paintings but also because Deakin himself was the subject of one of Freud’s greatest portraits (above) and because Deakin’s photographs capture Bohemian Soho in aspic for the mental tourist of...