I've been able to change the background colour of the folder tree but can't see a setting to do the same for the file list. Am I missing something?
Yes, you definitely are. Keep looking 
Actually, you've gone past it.
The File Display image is directly above where the Folder Tree image is defined.
OK Jon I kept looking and found it! But why does the area behind the actual file names remain white and only the area where there is no actual file name text changes to my chosen colour? This is not the case on the folder tree side of the display. When I change the background colour there it behaves as I would expect i.e. the whole panel changes colour.
By default the current sort field has a different background colour - you can change this in the Field Colors section.
Thanks.