Blue Peter: Behind the scenes

Blue Peter sends presenter Joel DeFries to Aardman's Bristol studios to see the BBC1 Christmas ident being made. He helps lead animator Merlin Crossingham and his assistant Will move Wallace and Gromit up the hill. It's a very long process, and when Will mentions that just half a second's worth of film is produced in one day, you get an idea of how long the 40-second piece took to make.