Forgetting the old adage about the two colours that should never be seen together, the London sitting room of accessories designer Wendee Ou combines walls painted in a pistachio green (try Sanderson’s Silver Frost or Whitstable Blue for similar) with upholstery in an equally serene shade of blue. Refreshingly simple, the green paint used here has grey tones that make the room feel calm, while white woodwork and cornicing make the space airy. Accessories combining blue and green hues bring the whole look together.