Operational officer test | Blue Peter
Blue Peter is back at Spy School. Six candidates attempt to become the CBBC intelligence officers who will have a once-in-a-lifetime opportunity to go inside MI5 headquarters.Tweet
Project Enigma - Cracking codes in London | Blue Peter
The competition winners use a replica working Enigma machine to crack their own puzzle set by GCHQ.
Project Enigma - GCHQ Tour and challenge | Blue Peter
The competition winners, get their first look inside GCHQ and are given their top-secret mission to crack.