Supermarine Spitfire. At Royal Air Force's service. Part one. The Type 224 Spitfire.

 

The Supermarine Spitfire was a British fighter of the World War II era. It is regarded as one of the best fighters of the war. It has its origins in an Air Ministry Specification; F.7/30 from October 1931 which sought an all-metal day and night fighter armed with four machine guns, a good cockpit visibility, decent high maximum speed and good rate of climb to replace the ageing Gloster Gauntlet. 
The Air Ministry favoured the usage of the Rolls-Royce Goshawk engine, although it wasn't exclusive, so any kind of engine could be employed. 
Bristol, Hawker, Westland, Blackburn and Supermarine submitted proposals, but only three were selected for prototype production: Supermarine Type 224, Blackburn F.3 and Westland F.7/30, with designs from both Bristol and Hawker being rejected. 
Given Supermarine's success in the Schneider Trophy contests, R.J. Mitchell (Supermarine's chief design), was confident in designing a high-speed fighter, so four months after receiving the specification, a monoplane design was submitted, the Type 224.

The Type 224 featured an inverted gull-wing, had a fixed landing gear encased in large fairings and the fuselage was of monocoque construction. It was armed with four Vickers Mk. IV machine guns, two in either side of the open cockpit and the whole fighter was powered by a Rolls-Royce Goshawk II piston engine rated at 600 hp of power.
After wind tunnel tests, Supermarine submitted theoretical performance data to the Air Ministry , suggesting that the aircraft would enjoy good enough performance, so the Air Ministry granted Supermarine a prototype contract. 
On 19th February 1934, the Type 224 took off for the first time, at the hands of Joseph "Mutt" Summers, chief test pilot of Supermarine. Its performance was, however, disappointing, with lateral stability problems caused by the wing design, so a series of redesigns were carried out to the model, among them, an enlarged fin. 
Mitchell proposed a series of improvements to the Type 224, such a new wing, tailplane and a new engine, which would increase performance, but the Air Ministry decided in favour of a new fighter aircraft, instead of a modification of the Type 224. In January 1935 further production was cancelled. 
On 25th May 1937 the only Type 224 was transferred to the Aeroplane and Armament Experimental Establishment at RAF Martlesham Heath, Suffolk to be used during the summer for target practice at Orford Ness, Suffolk.

Although the Type 224 was a failure, Mitchell pushed on and kept designing a fighter, with a complete redesign feature a new straight wing and a thinner airfoil shape. 
The new redesign quickly caught Air Ministry's attention, so in January 1935, shortly after cancelling production on the Type 224, they issued Specification F.37/34 for the sole purpose of covering a new design by Supermarine. This specification mentioned purposely Supermarines specification 425a drawing and, eventually, led to the design of the Supermarine Spitfire.
Supermarine asked the Air Ministry to reserve the name 'Spitfire' to be reserved for the Type 224 and it was adopted, however Mitchell disliked it, so it was later dropped.

Sources:
1st https://en.wikipedia.org/wiki/Supermarine_Type_224
2nd Putnam Books - Supermarine Aircraft since 1914