Hi Chris, I can't identify the part from the part numbers you provided, but some of these are also inspection stamps. More knowledgeable forum members might be able to help with the part numbers.

From looking at the picture, it is clearly a riveted bracket or stringer of some sort. If you could probvide information as to where exactly your mate found it, then a co-relation between its location and known crash sites in Scotland can be made. The Majority of wartime crashes in Scotland have been identified and many have been visited and are well known to hikers and researchers alike.