were two Armstrong Whitworth Whitleys belonging to 419 Flight RAF, which was formed in September 1940. In 1941, the flight was expanded to become No. 138 Squadron RAF. In February 1942, they were joined by No. 161 Squadron RAF. 161 Squadron flew agent insertions and pick-ups, while 138 Squadron delivered arms and stores by parachute. "C" flight from No. 138 Squadron later became No. 1368 Flight of the Polish Air Force, which joined No. 624 Squadron flying Halifaxes in the Mediterranean. By the later stages of the war several United States Army Air Forces squadrons were operating Douglas C-47 Skytrains in the Mediterranean, although by this time their operations had passed from SOE proper to the "Balkan Air Terminal Service". Three Special Duties squadrons operated in the Far East using a variety of aircraft, including the very long-range Consolidated B-24 Liberator. RAF Tempsford Nos. 161 and 138 Squadrons were based at RAF Tempsford in Bedfordshire though No. 161 Squadron often moved forward to RAF Tangmere, close to the coast in West Sussex, to shorten their flights. The airfield at Tempsford became the RAF's most secret base. (Tempsford had been rejected for Bomber Command's purposes by Harris in March 1942, as it frequently became waterlogged.) RAF Tempsford was designed to look like an ordinary working farm. The SOE used Tangmere Cottage, opposite the main entrance to the base. SOE agents were lodged in a local hotel before being ferried to farm buildings, the "Gibraltar Farm" within the airfield's perimeter track. After final briefings and checks at the farm, the agents were issued firearms in the barn, and then boarded a waiting aircraft. The squadrons' first task was to take agents to France who could select suitable fields for their aircraft. Most of these agents were French expatriates, some of whom had been pilots in the French Armée de l'Air. Once the agent was in place and had selected a number of potential fields, 161 Squadron delivered SOE agents, wireless equipment and operators and weapons, and flew French political leaders, resistance leaders or their family members, and downed allied airmen to Britain. Between them, the two squadrons transported 101 agents to, and recovered 128 agents, diplomats and airmen from occupied France. 161 Squadron operations 161 Squadron's principal aircraft was the Westland Lysander. It handled very well at low speed and could land from touch down to turn around in only . It