with US equipment - prototype of Mk IV. Bolingbroke Mk III Floatplane conversion of sixteenth Bolingbroke Mk I, with two Edo floats. Bolingbroke Mk IV Twin-engine maritime patrol bomber aircraft, equipped with anti-icing boots and a dinghy, also fitted with American and Canadian instruments and equipment, powered by two Bristol Mercury XV radial piston engines, 134 built. Bolingbroke Mk IVW Sub-version of Mk IV powered by two 825 hp (615 kW) Pratt & Whitney SB4G Twin Wasp Junior radial piston engines as contingency against possible shortages of Mercury engines. The Mk IVW's performance was below that of the Mk IV and the supply of the British engines was maintained so production returned to the Mk IV after only 15 aircraft were built. Bolingbroke Mk IVC Version of Mk IV with 900 hp (671 kW) Wright R-1820 Cyclone engines not requiring high octane fuel. One built. Bolingbroke Mk IVT Multi-purpose trainer aircraft. A total of 350 built powered by Mercury XV engines, followed by a further 107 powered by the low-octane fuel Mercury XX* engine, giving a total of 457 built, with a further 51 cancelled. Six Mk IVT were converted to dual controls. A further 89 were converted to Mk IVTT Target Tug with the addition of winching gear in the rear cabin and target drogue storage in the bomb bay. Operators Royal Canadian Air Force Operational Squadrons of the Home War Establishment (HWE): No. 8 Squadron RCAF - Used Bolingbroke Mk I and Mk IV (Dec 40 – Aug 43) No. 115 Squadron RCAF - Used Bolingbroke Mk I (Aug 41 to Dec 41) and Mk IV (Nov 41 – Aug 43) No. 119 Squadron RCAF - Used Bolingbroke Mk I (Aug 40 - Aug 41), Mk IVW (Aug–Nov 41) and Mk IV (Nov 41 – Jun 42) No. 147 Squadron RCAF - Used Bolingbroke Mk I and Mk IV (Jul 42 – Mar 44) The following HWE squadrons only had small numbers of Bolingbrokes on strength: No. 13 (OT) Squadron RCAF - Used Bolingbroke Mk IV (Oct 41 – Jun 42) No. 121 (K) Squadron RCAF - Used Bolingbroke Mk IVTT (Target Tug) (Aug 42 – May 44) No. 122 (K) Squadron RCAF - Used Bolingbroke Mk IVTT (Target Tug) (Aug 42 – Sep 45) No. 163 (AC) Squadron RCAF - Used Bolingbroke Mk IV (Mar–Jun 43) (BR)-Bomber Reconnaissance; (OT)-Operational Training; (K)-Auxiliary; (AC)-Army Co-operation British Commonwealth Air Training