Today after work I did two more houses with the thermal imaging camera. One was a 1991 terrace and the second was a 1905 semi.
The semi had cavity walls, a truly advanced feature for the period and was generally very good for a house over 100 years old. The newer house was warmer - mostly because it was a mid-terrace - but in many respects it was not that brilliant - as the owners readily admitted. The good thing was in both cases there were easy things to suggest that should make them more efficient so I hope I've done some good.
My thermal imaging camera is now on charge for tomorrow night.