I compared the spike with a standard enfield spike bayonet to see if there was anything special about the placement of the "1". Doesn't appear to be anything special about that spot. Perhaps it is just a makers mark. Length of the spikes are not exactly the same but it's only about a 16th of an inch (1 or 2 millimeters) and could just be a production difference. Overall length of the spike of the sten taking into consideration it's full length where welded to the tube is much longer. I also see no coloration differences around the "1" indicating any different treatment of the metal there but just might not be visible.