Work began in the Mansion and its outbuildings, with a staff of around 150 people. As more and more people arrived to join the codebreaking operations, the various sections began to move into large pre-fabricated wooden huts set up on the lawns of the Park. For security reasons, the various sections were known only by their hut numbers. The first operational break into Enigma came around the 23 January 1940, when the team working under Dilly Knox, with the mathematicians John Jeffreys, Peter Twinn and Alan Turing, unravelled the German Army administrative key that became known at Bletchley Park as ‘The Green’. Encouraged by this success, the Codebreakers managed to crack the ‘Red’ key used by the Luftwaffe (German air force). In addition to German codes, Italian and later Japanese systems were also broken.