Christie was recruited by MI6 and in 1927 served as air attaché in Berlin. In 1930 he started a business career while continuing to spy on Germany. He owned a house on the German-Dutch border which he used as a base for his undercover work.
Christie had met Hermann Goering while at university at Aachen. He was also a close friend of Erhard Miltch, Goering's deputy as State Secretary in the Reich Air Ministry. In this post Milch was responsible for managing armament production. This enabled Christie to move in official circles. He also obtained information from the anti-Nazi politician, Carl Goerdeler, Hans Ritter, a government adviser and German diplomats, Hans von Herwarth and Wolfgang Putlitz.
In February 1936 Christie was able to give detailed information concerning current aircraft production in Germany and the long-term plans for the Luftwaffe. Christie also provided details of the proposed invasion of the Rhineland.
Christie had a meeting with Hermann Goering on 3rd February 1937. He immediately reported his conversation with Goering and included information that Germany intended to take control of Austria and Czechoslovakia. He also told Christie that Germany mainly wanted "a free hand in Eastern Europe."
In March 1938 Christie told the British government that Adolf Hitler would be ousted by the military if Britain joined forces with Czechoslovakia against Germany. Christie warned that the "crucial question is 'How soon will the next step against Czechoslovakia be tried?' ... The probability is that the delay will not exceed two or three months at most, unless France and England provide the deterrent, for which cooler heads in Germany are praying."
Neville Chamberlain refused to act on this information and instead continued with his policy of appeasement. On 29th September, 1938, Chamberlain, Adolf Hitler, Edouard Daladier and Benito Mussolini signed the Munich Agreement which transferred to Germany the Sudetenland, a fortified frontier region that contained a large German-speaking population. When Eduard Benes, Czechoslovakia's head of state, who had not been invited to Munich, protested at this decision, Chamberlain told him that Britain would be unwilling to go to war over the issue of the Sudetenland.
I asked the General straight out "What is Germany's aim in Europe today?" Goering replied "We want a free hand in Eastern Europe. We want to establish the unity of the German peoples (Grossdeutschegemeinschaft)'. I said "Do you mean to get Austria?" Reply "Yes". I said "Do you mean to get Czechoslovakia?" Reply "Yes".
The crucial question is How soon will the next step against Czechoslovakia be tried? ... The probability is that the delay will not exceed two or three months at most, unless France and England provide the deterrent, for which cooler heads in Germany are praying.