Ok, we finally got there.
Here's the situation:
I can start a brand new, clean drawing and select the print style table I want to use during the drawing set-up process.
But, when I try to select a style for a particular layer, my only option shown is 'normal'
Unless, that is, I previously select one item of the drawing (a line, a wall, whatever) and select the print style for that item in it's properties dialogue.
That seems to force TurboCad to then recognise that a print style exists and makes it available from then on via the Layer manager.
So we now have the ability to output in colour and Black & white, via the layer properties.
Still have an issue with 'run as administrator' though as this definitely causes the Print Style Manager to malfunction on my machine. Open TurboCad normally and it works fine.
Are there any known conflicts with other software, such as Norton?
Thanks all for the useful suggestions and help.