Hello Dave,
Maybe of interest for you. For more than 10 years now I'm researching the crash of one of the first PR Spitfires(N-3069) your uncle worked with. Can provide info regarding this a/c and its crash near German/Dutch border east of Arnhem.
Kind regards from the Netherlands
Sander
Foundation Aircraft Research group Achterhoek(ARGA)
www.arga-nl.nl