Posted 14 June 2010 - 03:48 PM
I expected that it would be a .jpg, but as I had tried to use the search tool to find one of the default wallpaper files (whose name and location I knew) without success, I didn't fancy my chances with an unknown file in an unknown location!
The reason for asking the question is that the backup is on a USB ext drive, in amongst about 170GB of other files -- including 3 years worth of photos! (although I do know exactly where they are) -- and a file extension search would take a very long time.
Fortunately I have now found it, by chance, while copying some other user files.
Being a firm believer in thingy's Law, if I hadn't posted this request for help I wouldn't have found it!