I also haven't been sure who's made Iwan Ries shop pipes. I was there on a work trip back in, oh, I don't know, maybe 2011 or so? I picked up an inexpensive, un-branded churchwarden that I love, but I've never known who made it.
I‘ve picked up a couple IR trade pipes in my visits to Chicago and never thought to ask who made them. They look, feel and smoke very similar to pipes made by Tim West of Columbus, but I’m not certain.
Bari made a lot of Iwan Ries’ branded Danes.
Yours does look to be more of a Stanwell for sure though.
Here’s their catalog page from I forget when, listing one of my IRC pipes I got from my father (875 G).