Actually, reminds me of the mid-war anomaly I particularly like of Lithgow's. Sometime in 42/43, the * stamp must have worn, been broken or being remade - whatever - so they stamped the * with the Star and A inspection mark instead! I sadly no longer own one, but always look for this little anomoly.
If it was me identifying such a rifle for registration I would put down the serial number as MK111 to save applying a number. How many SMLEs have we seen registered using their rack or batch numbers?
As an afterthought, FR allow the serial number on collectable examples which would be devalued by stamping/engraving, to be on a metal tag attached to the firearm in a manner so the tag is not readily removed.