Anyone recognize this star stamp from a No4 MkI receiver ring?

I don't remember seeing this five pointed star mark before, and can't find it in any reference books I have.

Does anyone know its origins?

Note that the crown of the BM proof mark is coincidentally struck right on top of the star.Attachment 37982Attachment 37981

Its an extremely common mark on No4s, and occurs with or without a "W" in the centre. My own view is that it is an inspection mark applied when the rifle was checked before being put into depot storage at Weedon.