For nearly 50 years, the Scottish collection at Edinburgh’s National Galleries has been housed in a gloomy subterranean space beneath the main gallery, rarely visited, never celebrated. If you didn’t know it was there, don’t be ashamed. Just 19 per cent of visitors ventured into the bowels to find the jumble of Scottish paintings, dimly lit and hanging on colour-sucking, mucky green walls above a depressing brown carpet.