Original Mounting Post for BREN LMG.
It is designed to socket into a hole just over 1.05" OD. 1.05" is the diameter of the post socket.
These came out of Greek arsenals are are likely for mounting a BREN LMG on vehicles or other fixed positions.
MAY HAVE MINOR PITTING
This item has been stripped of finish originally it appears to have been painted British Army green.