A bit more progress today, Faultmate Vehicle Explorer runs on a Windows 10 Home 64 bit V1903 Tablet/Notebook.
My USB to serial adaptor is a Prolific PL-2303XA/HXA. Prolific say this chip is not supported by Win 10 so they do not supply a driver. What the hell, nothing to lose so I plugged it in anyway, Windows reported that the chip is obsolete and then proceeded to install a driver that seems to work, at least I can access my Faultmate on the bench.
More testing tomorrow on the car if it's not raining.
As an aside, I have spent a day now turning off features I regard as undesirable, tracking, personalised adds, Cortana, and the cloud and a number of other things. Some feature have a habit of turning back on
think I've cracked it now,