P9565 Supermarine Spitfire I NP0277.jpg
One of the stranger mods applied to the Spitfire was this extra 30 gallon fuel tank, fitted asymmetrically to the port wing only. It was trialled on MkI P9565 Supermarine Spitfire as seen here in October 1940, and despite handling problems, it was ordered and fitted to approximately 50 MkIIs. These MkIIs flew escort missions for Blenheims on daylight raids over France in 1941 when beyond the range of standard Spitfires. The eventual solution of course was found in slipper tanks under the fuselage or even external drop tanks.