Ah but there are No.4 MkII Singer made bayonets with the "G crown R" marking on the socket, I have one. It came out of a large box of otherwise unremarkable grease covered No.4 bayonets about 10 years ago. If I can talk my daughter into taking a picture I will post it. It is simply an early MkII. and was purchased with scabbard for $2.50, the same price as all the others in the box.