Graham.
Do a google search for 'Tamiya Spraywork' it's an airbrush and compressor made by tamiya. It runs from a 7.2 volt battery and works a treat. I've had one since the 80's and it still works. The new one looks really nice, although I believe you'll have to buy it from overseas. Still it's very well priced for what you get and you don't need a separate compressor.
Found it here :
http://tamiya.com/english/products/7...basic_comp.htm
mmmm, nice.