Every August, Edinburgh becomes a different city. The population roughly doubles. Every spare room in a ten mile radius is rented out to a comedian, a theatre troupe, or a solo performer who has been working on their show for two years and is quietly terrified. The Royal Mile turns into a parade of flyering, shouting, singing and general theatrical desperation. Cowgate stays open until four in the morning. And scattered across every church hall, basement, converted car park a