Personally I think it is a post war Souval piece.
It has the dropped 3 on the obverse that is seen on wartime examples but it also seen on postwar pieces.
What puts me off is the LDO number within a lozenge as I have never seen that one before and the pin and hook set up.
Here is a great piece of work on EKs
All the best
This hardware was only used post war by Souval and St&L.