Hi
I am a newby to this site and need some help to ID a piece of crashed plane that a friend brought me back from a hiking holiday in Scotland. She found the piece on its own and it seems to have a lot of numbers on it!

From the Photo attached it has:

a circle with HP 21B (or an 8) and then the number L129PR94157 (or L1297694157?) and then at the far end of the piece MJ142 and then another number partially obscured by crash damage that lools like _ _ B51793 (or 8). Can anyone help?