London Maker

Although the letter states 1912-13, the makers mark suggests Arthur Sibley, in fact it looks exactly like it - but I think he stopped working much earlier.
Any suggestions please?

Sibley apparently stopped working c1879 so it isn’t him. I note that Asher Solovitch registered an identical mark in 1898 and 1905, but as a gold worker. Culme doesn’t have much to say about him so I don’t know how serious a contender he is. My only other thought is an unregistered mark of Adolph Scott but I don’t have any evidence of a Scott mark like this at any of the other assay offices in the 1912 period.

Many thanks for that.
I realised initially it wasn’t Sibley because of the date, although the actual mark, to me looks identical. (I still know it’s NOT Sibley though! )
Thanks for alternative suggestions.
Best regards