Well spotted Alton11...

I would not have made that out in a lifetime, but I do have a piece I bought directly from Stephen, at Broadfield House in 2001, when he was working with Ian MacDonald there, on a studentship.
He asked me if I'd like him to sign it, which I obviously did.
He did struggle a bit with the engraver, had a lot of trouble making his mark, but I have just brought it out and compared it with the image above.
It's not a bad match at all.
I think you've cracked it!