The Supermarine Spitfire is regarded by many as the most beautifully designed single seat fighter to appear during WWII. The Spitfire went through numerous major and minor changes throughout its long production life. Early improvements resulted in the Mk.V series of Spitfires which became the most widely produced versions of all Mks. The main improvements were the furnishing of three wing armament configurations, and the use of the more powerful Merlin type 45 engine. The most numerous Mk.V was the b winged version which had a mixed armament of two 7.7mm machine guns and on 20mm cannon in each wing.
The Spitfire that demonstrated such superb performance over its homeland, was also urgently required for operations overseas. One of the better-known versions was the North African prepared Spitfire designated TROP, for Tropical. The biggest problem in desert operations was the intake of abrasive sands into the engine, which quickly wore out moving parts. To overcome this difficulty a Vokes air filter was affixed over the carburettor intake.
Although the filter was successful, its large mass reduced the aircrafts speed. The problem was solved by the local maintenance unit stationed at Aboukir, who designated a smaller more streamlined unit that was equally effective. The clipped wing versions, which had better low altitude manoeuvrability, were commonly seen in North Africa.