Hi Dan,
>The contra-rotating prop isn't normal for a Spit 19. They were going to use it for some speed record attempts and had clipped wings on it as well.
Hm, from what I read the Spitfire XIX in question until recently had a standard propeller but was grounded due to either propeller or engine trouble. When they found a complete Shackleton (?) power unit with contra-rotating propeller for less than it cost to fix either the broken propeller or engine, they simply went the path of least resistance.
That's from memory only, I'd have to dig through old magazines to make sure it's accurate :-/
Regards,
Henning (HoHun)