After covering weighty issues like death love religion and spam javelins the King of Edinburgh 6 Music is in a frivolous mood with this show about daftness whether the term cool comedian is an oxymoron bouncing joyously on the sofa and how Herrings whole career is a failed attempt to top a piece of visual slapstick comedy he came up with at 16 Can he revisit the joke thirty years on or will it smash his old bones