Kilroy was here. The world’s most well-known graffito. Bald-headed geezer with banana-nose peeping over walls, fingers clutching sides to steady a pea-eyed gaze.   In WWII, the average Joe’s default method of planting the flag, on every available wall, barn, railway carriage. Discovered on so much captured US weaponry, Hitler thought it a code name. Even Stalin found Kilroy perving in his bathroom.   Known as Mr Chad in the UK, Private Snoops, The Goon and Watcher. A variety of accompanying slogans included: Wot, no sugar?  Wot, no Fuehrer? In WWI Australia, Foo Was Here. In Africa, Smoe & Clem.…