Interesting. Thanks for the information. I have several of these bayonets and I’m almost certain that I have at least one of the “S M C” variants.

 

Fascinating.
Graham Priest in "The Spirit of the Pike" pg. 52, asserts that S M was the only logo used on the No4 MkI bayonet, with the S.M.C. trademark used on Sten Machine carbines, not on bayonets.
Looks like one has snuck through & is hunky dory. Maybe check the length of the spike to confirm.

 

Had a quick look at some of mine & have included a photo of the front of the socket.

 

Graham mentioned after the book came out that he could not find an example in time for print. There is a second theory that the "C" removal was intentional, as some of Singer's initial Rifle No. 4 subcomponents were also marked SMC. As with every book and every author, once something is put to print, another undocumented example appears. I have located at least one other Stevens-Savage marking type that was not included in his book, which will be included in my Rifle No. 4 book coming out at the end of the year.

 

I was one of the many who emailed Graham when the book was released. His explanation was stated as above. He also sent me a correction sheet to slip into the book. Unfortunately it somehow disappeared. But thanks to forum members I do have some corrections in the pages.
And I no longer loan my books out!

Back to topic: I have a tough time fathoming Singer only having one die on hand for marking bayonets. There must be something deeper to the missing C.
Dies fail and get repolished. So polishing it away and leaving the marking off center I can understand. But, only one die?

 

Glad to hear of you both questioning Graham regarding the No4 MkI marks.
I checked with Skennies & Richardson's 'British & Commonwealth Bayonets', shortly after posting.
On pg. 215 it is made quite clear the factory markings could be both S.M.C. or S.M.