On Sep 26, 2:20*pm, jim wrote:
except the wall will act as a heatsink down through the foundations
and up into any more wall above it?

I'd concentrate on the inside.
I agree about not bothering to insulate the outside. I still think the
idea of internal insulating block wall is worth looking at.
Alternatively, if space is such an issue why not make a small wall
built with side on bricks. Leave a centimetre air gap so that it
projects about 75mm from the existing wall. Those bricks will will
then become the thermal store. Surely someone can work out the
resulting heat loss.

dave