The Poles had broken Enigma in 1932, when the encoding machine was undergoing trials with the German Army. But when the Poles broke Enigma, the cipher altered only once every few months. With the advent of war, it changed at least once a day, giving 159 million million million possible settings to choose from. The Poles decided to inform the British in July 1939 once they needed help to break Enigma and with invasion of Poland imminent.
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.