Pink Spitfires are more common than you might at first imagine...
The Photo Reconnaisance Pink Spitfires were used for medium level recce work, where the pale pink colour helped to 'hide' them against haze or cloud background. These Spits were fully armed, as they were more likely to encounter enemy fighters, whereas the PRU Blue aircraft were un-armed, relying on altitude and speed to get out of trouble. Earlier in WW2, some recce Spits were finished in a pale, off-white colour, for operations below cloud.
A similar pink colour, known as 'Desert Pink', was used on RAF Tornado, Buccaneer and Jaguar aircraft, in the medium to low-level strike role, during the first Gulf War, where the aircraft blended in with the desert sky, and the terrain. This shade was slightly different to the wartime Spits, being a pinkish sand colour, and was developed as a result of the SAS using a pink finish on Land Rovers used in the desert, where it was found this colour really blended in, with the surroundings, and the pinkish effect of the UV rays in the haze.
And think of the embarrasment of being shot down by a pink Spitfire.