I think the stamps on Sheffie razors indicate a Royal Warrant granted and were not Royal Cyphers. Royal Cyphers appear to be something else again and used differently.
https://en.wikipedia.org/wiki/Royal_cypher
My guess would be that the Royal Warrant was used during the reign/lifetime of that particular King or Queen. If the succeeding King or Queen did not grant a Royal Warrant to that firm then that stamp was omitted.
It is times like this that Neil Miller's help is sorely missed in clarifying these things.
Bob