51st (London) Heavy Anti-Aircraft Regiment was a volunteer air defence unit of Britain's Territorial Army from 1922 until 1955. During World War II it served in Norway, The Blitz, North Africa (when detachments defended Crete and Tobruk), and finally in Italy until the end of the war in Europe, by which time a proportion of the regiment's personnel were African soldiers, and the guns were engaging ground targets rather than aircraft.