I was looking for another unusual colored Brooks product today and found an answer to the query I'd had back in 2019. Here's a page from Radavist from 2013 showing some limited edition Brooks Professionals with big copper rivets in unique colors including a maroon/cordovan/dark red. This was evidently what I'd seen back in the 'teens and mis-remembered as a Champion Special. Though my faded green saddle definitely is a Champion Special, I guess from a different series. When Brooks does these specials the editions really are limited! So if you see one you like, better jump on it.

https://theradavist.com/new-offerings-from-brooks