I just stumbled upon this "old" thread and thought it was well worth putting it back on top again.
What a terrific picture!
Looks like Morris Commercials C4 Wireless House Type Mk2 to me.
Geoff, did you try the Imperial War Museum? They have lots of pictures and just maybe......
It's a pity that not much can be seen of the scenery, so it will be hard to find the exact location when I am in Normandy for my holiday.
Alex