Behind-the-scenes tales of entertaining at royal residences, with the Buckingham Palace party that almost went up in flames and the secret messages for Kensington Palace's unwelcome guests. Wayne Sleep recounts the extraordinary tale of being snuck into Kensington Palace to teach Diana, Princess of Wales, how to dance, while historian Kate Williams takes us back more than four centuries to the Elizabethan palace where the secret to entertaining was some surprising sweet treats