First Spit to use the extented pointed wingtips for high alt flying was the Spitfire VI, another of the small production models for a specific purpose, which was high alt stuff.
The VI was a modified Spitfire V with a 4 blade prop, pressurized canopy and extended wings and a modified single stage Merlin. The canopy of the VI had to be bolted on over the pilot for the pressurized cockpit to work. Needless to say, not very popular and often flown without the canopy. Only about 100 built and not a huge success as the single stage merlin just couldn't do the job up high.
Second version was the VII that had two stage Merlin optimized for high alt work, the pointed tips and pressurized cockpit with sliding canopy. The VII was another batch of just over 100 built Spits. As Kev mentioned by D-Day the VIIs were being flown with standard wingtips and often used for ground attack. There just weren't any targets up high.
Both VIIIs and IXs could be found with the pointed tips as well.
A couple of Spit Vs were locally modified in the Med with pointed tips to chase high alt recce birds too.
Dan
