Nicholas Allan is well-known for two things; firstly for the being the wonderfully funny author of such children's bestsellers as The Queen's Knickers . Secondly, for being able to gatecrash even the most exclusive of parties. It's a skill that has brought him into contact with the great, the good and the greedy-from Mick Jagger to Princess Anne. It's allowed him to drink Tattinger champagne at the Savoy, nibble Caviar canapes in private members clubs,...