The Hudson Mk. III, which first appeared in August of 1940, combined the airframe improvements of the Mk II with more powerful GR-1820-G205A engines, rated at 1200 hp for takeoff and 1050 hp at 7500 feet. The engines drove a set of constant-speed propellers. An additional flexible 0.303-inch machine gun was added in a retractable ventral position and one 0.303-inch flexible gun was mounted in each beam position. The bomb load was increased to 1600 pounds.
A total of 428 Mk. IIIs were built against British contracts. RAF serials were T9386/T9465 (c/n 414-2421/2482, 2501/2518), V8975/V8999 (c/n 414-2519/2543), V9020/V9069 (c/n 414-2544/2589, 3711/3714), V9090/V9129 (c/n 414-3715/3754), V9150/V9199 (c/n 414-2755/3804), V9220/V9254 (c/n 414-3805/3839), AE485/AE608 (c/n 414-3840/3963), and AM930/AM953.
During the course of production, extra fuel tanks were added to to 241 of these planes, increasing fuel capacity from 644 to 1028 US gallons. These were redesignated Mk.III(LR), with the initial production aircraft then becoming Mk.III(SR). The 428 British-ordered Mk.IIIs were distributed to the RAF (371 aircraft), the RCAF (three with British serials), and the RNZAF (54 with serials starting with NZ2001). Some of the Hudson Mk.IIIs were later modified to carry Mark I airborne lifeboats on air-sea rescue missions.
The BOAC received a few Mk.IIIs for use as transports. Among these were V9061 (G-AGDC Lock Lomond), AE581 (G-AGDO Loch Loyal), and two unidentified aircraft (G-AGDF c/n 3772 Loch Leven and G-AGDK c/n 3757 Loch Lyon). Two ex-BOAC aircraft (G-AGDC and G-AGDK) were returned to the RAF as Hudson C.Mk.IIIs and received new military serials: VJ416 and VJ421.
Engines: Two Wright R-1820-G205A air-cooled radials, rated at 1200 hp for takeoff and 900 hp at 15,200 feet. Performance: Maximum speed 255 mph, cruising speed 223 mph. Service ceiling 24,500 feet. Maximum ange 2160 miles. Weights: 12,536 pounds empty, 18,500 pounds loaded, 20,000 pounds maximum. Dimensions: Wingspan 65 feet 6 inches, length 44 feet 4 inches, height 11 feet 10 inches, wing area 551 square feet. Armament: Two fixed, forward-firing 0.303-inch Browning machine guns mounted in the nose above the bombardier's windows plus two 0.303-inch machine guns in a dorsal Boulton Paul power turret. One flexible 0.303-inch machine gun in a retractable ventral position and one 0.303-inch machine gun in each beam position. Maximum bomb load of 1600 pounds could be carried in an internal bomb bay.