Like other countries. Britain turned its domestic auto industry to making military vehicles during the war years.
After the jump, a brief look at a very basic utility vehicle.
I have to admit I know nothing about British cars of this era. But apparently the Austin 10 GRQ of 1939 was considered a suitable vehicle for modification into a light duty utility truck. The rear, that is, the back seats and boot area were cut away to allow for an open bed. So this is basically a small pick-up. It has a 22 HP engine, which sounds horribly under powered to me, but is apparently fairly standard for the period.
The Name “Tilly” is an abbreviation from “utility”. In other countries this would be known as a “Ute”. During the war years this would be a common vehicle at army bases and air fields.
This kit is by Tamiya. It represents an RAF airfield service vehicle.
Up Next: Messerschmitt Me163B-1 Komet
Plane Dave 
If Imy eyes doesn’t betray me, one of this cars appesrs in “The Eagle Has Landed”.
I don’t recall, but no doubt it could be appropriate. Even deep in Germany, if some were captured during the Battle of France they likely would have been used. My only question being that as a 1939 model, I’m not sure if many would have been attached to the BEF or RAF in 1940?
Which is sort of all beside the point! Filmmakers so often use just whatever is about right when making movies. Like that Bell helicopter in Luftwaffe markings. I’ll have to be on the lookout the next time I watch it.