Philip Larkin once remarked that Art Tatum, a jazz musician given to ornate, multi-noted flourishes on the keyboard, reminded him of ‘a dressmaker, who having seen how pretty one frill looks, makes a dress bearing ninety-nine’. If you substitute paintings of flower-beds and dappled sunlight for chromatic keyboard runs, something similar is true of the new blockbuster at the Royal Academy, Painting the Modern Garden.