In May 1940, the Vickers Wellington bomber was included in the list of aircraft declared a high priority by the United Kingdom's Ministry of Aircraft Production. Full-scale production of the Mk.IC (Type 415) model started in April 1940. This version said the final goodbye to the retractable ventral turret, favoring guns placed on the aircraft's sides instead. In place of the Frazer-Nash FN-25 turret, the plane featured two side blisters consisting of 7.7 mm Vickers Class K machine guns with 483 rounds each (7 flat pan magazines, standard capacity). The Mk.IC bombers of later series had the Vickers machine guns on the aircraft's sides replaced with 7.7 mm Colt-Browning Mk.II .303 belt-fed machine guns with 600 rounds each.
The nose and rear turrets remained the same as they were in the Mk.IA model. The standard payload was not changed either, with a load capacity of 4,500 lbs (2,041 kg). The standard bomb load was nine 500-lb (227-kg) bombs or two 2,000-lb (907-kg) bombs. The aircraft's engine was left unchanged.
A special model, the Type 423, was based on the Wellington Mk.IC; it was able to deliver one 4,000-lb (1,816-kg) extra-heavy Cookie Mk.I or Mk.II bomb to the target. To accomplish this, the central bomb bay doors were removed and the bomb bay itself was modified. The defensive armament remained the same.
The Wellington served not only as a bomber; the missions that it performed for the RAF Coastal Command were no less important. In January 1941, the Mk.IC began to be used as an anti-submarine patrol aircraft, although no design changes were made. In December 1941, the first torpedo bomber conversions were made.
The Wellington Mk.IC (TB) torpedo bomber was identical to the Mk.IC as far as its engine and defensive armament goes but could carry up to two Mk.XII torpedoes inside.
The first special anti-submarine model designed for the RAF Coastal Command was the Type 428 Wellington GR Mk.VIII (TB). Its structure had the airframe of the later Mk.IC series. The GR Mk.VIII (TB) scout bomber began production in the spring of 1942 in three versions: one version with radar, one version with a retractable searchlight (in place of a nose turret), and one version as a long-distance scout with extra fuel tanks installed in the bomb bay. All three, starting with the 66th production aircraft, were equipped with a torpedo mount like the Mk.IC (TB) model.
The Wellington torpedo bombers were used for the first time in the Mediterranean Sea at the end of December 1941. Anti-submarine models began to patrol the North Sea in May 1942. The first German submarine destroyed by these planes was sunk on July 6, 1942.
2,547 Mk.IC aircraft were produced, including 138 Mk.IC (TB) torpedo bombers and 271 GR Mk.VIII (TB) torpedo bombers.