Fairey Swordfish, part three, origins

As Fairey was a company that had already proven its talent to design and construct naval aircraft, in 1933 they started the design of an entirely new three-seater aircraft intended for the reconnaissance and torpedo-bomber. The project received internally the designation of T.S.R.1 (Torpedo Spotter Reconnaissance) with a biplane configuration and was to be powered by a single Bristol IIM radial engine which could yield 645hp of power. Fairey initially chose to keep the development as purely private while both customers and applicable requirements for the type were sought. The development of the T.S.R.1 was made in parallel to Fairey's activities regarding the Air Ministry Specification S.9/30, for which the company was, at one point, developing a separate but very similar aircraft, powered by a Rolls-Royce Kestrel engine instead and employing also a different fin and rudder configuration.
A respectable amount of contributions for the T.S.R.1 came from Fairey's independent design work on a proposed aircraft for the Greek Naval Air Service which had requested a replacement for the Fairey IIIF and Fairey IIIB, and also came from specifications M.1/30 and S.9/30. Fairey soon informed the Air Ministry about their work for the Greeks, whose interest had eventually waned, and proposed its solution to requirements for a spotter-reconnaissance plane. In 1934, the Air Ministry issued the Specification S.15/33 which added the requirement of the torpedo bomber role.
On 21st March 1933 the first prototype took off to the skies from Great West Aerodrome, in Heathrow at the hands of Fairey's chief test pilot Chris Staniland. It performed various flights which were used to test aircraft's flight characteristics, before being re-engined with with an Armstrong-Siddeley Tiger radial engine and switching back to the Pegasus engine again. On 11th September 1933 the first prototype was lost when it entered in an uncontrollable series of spins that crashed the aircraft with the pilot, fortunately, surviving the accident. Before this, as the prototype had shown favourable handling and flying characteristics, it was decided to proceed with a second prototype (T.S.R.II) which had been designed to fully comply with the Specification S.15/33.
On 17th April 1934 the second prototype flew for the first time, piloted by Staniland. Unlike the previous model, it was equipped with the more advanced version of the Bristol Pegasus Engine, an additional bay within the rear fuselage to counter the spin tendencies and the upper wing was slightly swept back to cope with the increased length of the fuselage together with other aerodynamic-related tweaks to the rear of the aircraft. During the flight test programme T.S.R.II was sent to Fairey's factory in Hamble-le-Rice, Hampshire, where it received a twin float undercarriage instead of its original wheeled one. It flew for the first time in this new floatplane configuration on 10th November 1934 and, after successful water-handling trials, it made a series of catapult launch and recovery tests on board HMS Repulse Battlecruiser. It was restored back to its original wheeled configuration before being handed over to the Royal Aircraft Establishment for an extensive evaluation process at RAF Martlesham Heath.
In 1935, after satisfactory tests were made at Martlesham, the Air Ministry placed a pre-production order for three aircraft. It was then when the T.S.R.II received the nickname of Swordfish. All three of them were powered by Bristol Pegasus IIIM3 engine, but adopoted a three-bladed propeller configuration instead of the two-bladed one employed by the previous two prototypes. On 31st December 1935, the first pre-production Swordfish made its maiden flight and on 19th February 1936, the second one. The third one was completed in floatplane configuration and underwent water-based service trials at the Marine Aircraft Experimental Establishment at Felixstowe, in Suffolk.

Sources:
1. en.wikipedia.org/wiki/Fairey_Swordfish
2. http://www.aviation-history.com/fairey/swordfish.html
3. Hall Park Books - Warpaint 12 - Fairey Swordfish
4. Signal Squadron - Aircraft In action 1175 - Fairey Swordfish in Action