Option to display touch keyboard in Windows 10 is completely missing when ruing on legacy tablet

I have installed windows 10 on an old tablet (Paceblade 200) and having installed the touch drivers I now find that I am unable to get the touch keyboard to show, and that the settings for the touch keyboard are completely missing from the settings app.

I have tried following the instructions detailed here:

The Windows 10 onscreen keyboard does not launch automatically

But the setting referred to is simply not present in the settings app.

The screen appears to emulate PS/2 mouse input, so perhaps any instructions that allow the touch keyboard to work with an ordinary mouse would also work in this case.