In 1935, following the successful completion of testing at Martlesham, an initial pre-production order for three aircraft was placed by the Air Ministry; it was at this point that the T.S.R II received the name "Swordfish". All three pre-production aircraft were powered by the Pegasus IIIM3 engine, but adopted a three-bladed Fairey-Reed propeller in place of the two-bladed counterpart used on the earlier prototype. On 31 December 1935, the first pre-production Swordfish, "K5660", made its maiden flight. On 19 February 1936, the second pre-production aircraft, "K5661", became the first to be delivered; the final pre-production aircraft, "K5662", was completed in the floatplane configuration and underwent water-based service trials at the Marine Aircraft Experimental Establishment at Felixstowe, Suffolk.