661 Air Observation Post (AOP) Squadron Royal Air Force (RAF) formed up on 31 August 1943 at RAF Old Sarum, equipped with Tiger Moth and Auster Mk3 aircraft. In 1943 the Squadron was detailed to support the First Canadian Army, the senior Canadian operational formation in Europe during the Second World War. The Canadian Army formed up in early 1942, in order to replace the existing Canadian Corps, as the increasing number of Canadian personnel in the United Kingdom meant that two corps were required. The Squadron's 'C' Flight left for Normandy on 21 July 1944, being actively engaged in the 'Falaise Pocket', (an engagement fought from 12-21 August 1944 during the Battle of Normandy) followed by the rest of the Squadron, where they supported the First Canadian Army across the low countries and into Germany for the remainder of the war. The squadron was disbanded at Ghent, Belgium, on 31 October 1945.
Post-war the Squadron was reformed as part of the Royal Auxiliary Air Force ( RAuxAF) on 1 May 1949 at RAF Kenley but was disbanded on 10 March 1957 along with all RAuxAF flying squadrons. 661 (AOP) Sqn RAF became an Army Air Corps (AAC) squadron on 24 November 1969. 661 Sqn AAC deployed three times on Operation TELIC (Iraq), between April 2005 and May 2009 and on Operation OCULUS (the Balkans) between April 2006 and April 2007. They rotate deployment on Operation HERRICK (Afghanistan) with other AAC Light Utility Helicopter squadrons.
Squadron motto - 'Designe oculis ad caedem' meaning 'With my eyes I designate (the victim) for the slaughter'.
Squadron badge heraldry - A grenade enfiled by a compass ring.