These machines are relatively rare, but apparently quite robust and usable. Perhaps they are what MSX might have been? The Register says “Very possibly the second-best British micro of the early 1980s” in their history article.
Here’s a photo from a meetup, the Memofest, from Andy’s Memotech site:
Caption: " We saw the MTXPlus+ running a web server, from my NFX project"
You can run Fuzix too.
Here’s an image from The Register’s article:
Another great source of information and old adverts is Nosher’s collection: see here.