Many thanks Keith, for responding to this enquiry.
It is typical of me to get mixed up with my pico, nano and micros.
You are, of course, correct,... and I don't have a problem with that now!
So that is one that problem sorted! .... thank you.
The variable pots that I can find are only 10k or 100k.
Whilst there are thousands of choices for rotary pots, there seems to be a shortage of choice on the slider types ... at least at a price that makes the project cost-effective.
Is the paralleling of a 100k resistor with the 100k slider a non-starter?