Anyway I'm not talking about no insulation, I'm talking about doing it
where practical so I will be putting some insulation behind the
dry-lining but not so much that I generate lots of condensation.

Insulation helps prevent condensation. It doesn't cause it.

This group is really good on practical issues but seems to fall over at
least a little (don't want to be too rude) when it comes to theoretical
analysis. Maybe I should try alt.climatechange or something like that,
maybe theres even an alt.thermodynamics group!

If you propose an ELECTRIC underfloor heating system with no insulation in
alt.climatechange, if such a group exists, you are likely to be firebombed
by environmental activists.

Remember in your calculations that your basement floor is (a) at a much
elevated temperature and (b) loses two airsolid interfaces. It is solid
throughout, enabling straight conduction all the way through without having
to swap from solid to air, which provides considerable insulation in its own
right. Typically in an uninsulated floor situation, the floor surface
temperature itself is significantly lower than the room temperature, further
reducing actual heat loss.

Christian.