Lewin Alto Mouthpiece - any information

I just bought an alto mouthpiece on eBay for fun and I wonder if anyone in the forum can tell me more about it.

It is marked Lewin Table 4, London, Made in England
Silver plated.
Lawton-style ligature
Very large round chamber
Curved sidewalls
No baffle
It looks as if the ring round the shank was a separate item.

I have only played it briefly, and it sounds like a very clear classical mouthpiece to me.

There is some information on other SOTW threads that says that Lewin Bros, 17 Moor St., London W1, England, was a music shop in London, that sold stencil saxes (Martins).
So I'm wondering if this is a stencil mouthpiece.