Just put up a set of very tasteful purple LED outdoor lights from Habitat (eat your heart out Nigel!). Looking at them they are a blue & red LEDs in the same capsule and they must be on opposite cycles of the supply so they have a 50 HZ red and blue flicker which from a distance isn't noticeable but closer up means they have a disconcerting way of seperating out into a red light or blue light as you blink.