The old Psion case has begun to look a little tatty, so I thought I'd treat myself to a new belt case for my little Prawn, so I went on the hunt. I came across this one on Ebay: https://www.ebay.com.au/itm/225439458956
It doesn't have the Pro1 or Pro1X listed as a supported model, but the seller has lots of good feedback, it's the style I want, it's real leather, and I like the look of the thing, so fairly promising.
I took a punt and ordered one, selecting a phone model from the drop down list that I thought was there or there abouts on dimensions, (Xiaomi Poco M3). A bit longe