As a thoroughbred of the aviation world, the Supermarine Spitfire underwent constant development throughout WWII, with new versions of the fighter never too far away from joining RAF squadrons. 
 
The aircraft which fought the Battle of Britain were scheduled to undergo significant upgrade, however, whilst still in development, the Luftwaffe introduced their latest variant of Bf 109 fighter, one which was shooting down Spitfires in large numbers - urgent action was needed. 
 
The Spitfire Mk.V was effectively an upgraded Mk.II airframe, fitted with the latest version of Merlin engine, one which gave the aircraft greater high altitude performance and this variant would eventually equip more than 140 RAF Squadrons.