The Vickers Wellesley was notable for being the first RAF aircraft to incorporate Barnes Wallis's radical geodetic construction later found also in the Wellington bomber. It had originally been designed as a private venture monoplane for a Air Ministry requirment for a biplane torpedo bomber and featured long span wings, high aspect ratio (for maximum cruise efficiency), and prominent twin cockpits although some later examples had continuous canopy glazing. The Wellesley's claim to fame occurred when an aircraft from the RAF Long Range Development flight broke the world's absolute distance record in 1938 flying from Ismalia (Egypt) to Darwn (Australia), a 48-hour non-stop flight. Although largely replaced at home by the outbreak of war, Wellesleys saw extensive action in the Middle East, Africa, and Egypt before being relegated to shipping reconnaissance duties later.

The prototype Wellesley first flew on 30 January 1937 and entered service as the Wellesley Mk. I which equipped a maximum of 10 RAF squadrons shortly after. Various aircraft with continous canopy glazing were often referred to as the Mk. II but no other major variant was built.