British supermarket bosses like a bit of colour. Sir Ken Morrison, chairman of Wm Morrison, wears a charming yellow-and-black striped company tie when he visits the City of London; Justin King, J Sainsbury’s chief executive, has a suntan to match his company’s orange logo; and Sir Terry Leahy, Tesco’s chief executive, claims the love for his company runs so deep that if he were cleft in two, you would see nothing but the red, white and blue of Tesco.

However, in recent months, the only hue they want to talk about is green. “It’s the new black!” was the cliché trumpeted by Andy Bond, chief executive of Wal-Mart-owned Asda, at his very own environmental press show over the summer.