Thanks very-much to every-one for all this useful information, most interesting. It would seem that the No4 spike bayonet was refurbished more often than I thought. I do have several examples of this bayonet with serial numbers stamped on the bayonet but I don't have any with it on the scabbard. None of the stampings look professionally done more like Saturday morning in the garden shed done. The only other bayonet which I have seen with what appears to be rifle serial numbers stamped on the bayonet is the Mosin Nagent bayonet. I believe that this bayonet was not always able to fit every combination of model of the rifle that it was intended for?