Air vice marshal Park was in commanded of No. 11 Group RAF during the battle of Britain responsible for The fighter defence of London and southeast England, in April 1940. He organized fighter patrols over France during the Dunkirk evacuation and in the Battle of Britain his command took the brunt of the Luftwaffe's air attacks. After the battle he was sent to Training Command because of political back stabbing by other officers. In January 1942 Park went to Egypt as Air Officer Commanding, where he built up the air defence of the Nile Delta. In July 1942 he returned to action, commanding the vital air defence of Malta. From there His squadrons participated in the North African and Sicilian campaigns. In February 1945 Park was appointed Allied Air Commander, South-East Asia, Where he served until the end of the war.