The place we rent is terrible for overheating as you say Fred single layer of hollow breeze block has a low thermal mass that allows the heat through quite quickly but still retains enough heat to radiate at night so you get the worst of both worlds.

We also unfortunately are on a corner and we get a lot of sun all day plus we would do with the place being painted white to reflect the heat but it's blue and absorbs a lot.

I like the heat most of the time but it does become oppressive.

We talked before about families that close all the windows and run electric fans all night not realising that they are slowly heating the room up.

Next time I am over I am installing an extractor fan above the vent over the kitchen area as that will encourage air flow through the house. A lot of days if there is a bit of a breeze it's great, so I just need an artificial breeze I think but one that physically moves the hot air out of the building rather than just moving it around.