Turning the envelope over, his hand trembling, Harry saw a purple wax seal bearing a coat of arms; a lion, an eagle, a badger and a snake surrounding a large letter 'H'. HARRY POTTER has never even heard of Hogwarts when the LETTERS start dropping on the doormat at number four, Privet Drive. Addressed in GREEN INK on yellowish parchment with a PURPLE SEAL, they are swiftly confiscated by his…