Today Valerie and John go behind-the-scenes at Westminster Abbey to see the preparations being made for this week’s Royal Wedding. More than 500-million people in five continents are expected to be viewing on Wednesday, and the Wedding will be televised ' live ' to 16 different countries. The BBC will be using 50 cameras and 14 mobile control rooms to cover the event, and in today’s Blue Peter you can see where the cameras are hidden in the Abbey.