Yep makes sense, there's a thermostat inside the HVAC box which is intended to stop the whole lot freezing over - so that may have just been keeping the system offline.
This is where we proud owners can upload information and pictures of our pride-and-joys (their Exige that is..)
Had to make an essential journey so took the fun car. AC works well still, I get too cold if I have it on for a couple of minutes. Tested whether I could get it down the driveway at my parents' new house. The answer was no, it's too low. I got halfway down before it started skimming the splitter and the 2nd half of the drive is worse! Guess I'll have to visit them in the practical car in the future instead.