Only a few days after Poett arrived in Britain, war had been declared on Germany and the Second World War had begun. He travelled to the regimental depot in County Durham, and after two weeks at Brancepeth Castle running troop exercises, he was informed that he had been promoted to the rank of major and appointed a General Staff Officer Grade 2. Poett would be attached to a branch of the War Office known as Staff Duties 2, and his specific duties were concerned with allocating weapons to British Army units positioned throughout the different theatres of war. In early May 1940, Poett was sent to the General Headquarters of the British Expeditionary Force, and when he returned to Britain at the port of Dover he was informed that the invasion of Belgium and France had begun during his journey. Poett appealed to the War Office to be released from staff duties and assigned to a division in the field, but it was not until the Dunkirk evacuation was over that a replacement was found for him. He was then assigned as the GSO 2 for the 2nd Infantry Division, which had only recently returned from France. The division was situated in East Riding and was responsible for the defence of a large section of Yorkshire coast; as a result a number of anti-invasion exercises were conducted by the division, and there were also a number of invasion warnings. One such alert took place when Poett was in Woking, where his wife had just given birth to his son Simon.