Ever since the Bauhaus in Germany abolished colour as decadent and fussy back in the 1920s, architects and designers who think of themselves as progressive have favoured grey and its variants as the only acceptable accompaniment to plain black and white. A few years ago, a popular interior decorator published a promotional booklet suggesting colours to enhance your home and listed “taupe” and “beige” as enlivening possibilities. The only bright colour in her brochure was the scarlet of her fingernails.