I ventured into the Purple Empire. Gliding and soaring through dappled sunlight, this magnificent Purple Emperor in Savernake Forest made me feel as if I had been transported to the tropics. The Emperor's purple is not a pigment; rather it is formed by refraction of light from the structures of his wing scales. Purple can only be seen when the wing is at the right angle relative to both the observer and the sun, making it tricky to photograph simultaneously in all four wings. His Imperial Majesty is an aristocrat amongst British butterflies but his tastes are far from fastidious. This one was partial to a tasty dog turd.