Old trunk lock (post for NickinNZ)

The top pic is oriented correctly, and this is how it looks right behind the lock cover plate. In the top pic I had cleaned up the metal parts in a tumbler. But if you look, the key just needs to push the metal parts at the top right away from the center post about 1/4” and that opens the two latches.

The second shows both the cover plate and the internals beneath oriented correctly, and in their original condition. They cleaned up really nicely! Maybe this can help you get into your trunk Nick!!