So we ordered a new element, and as a treat a new thermostat, to try and regulate the temperature a bit better. Since purchasing an oven thermometer I have found the oven to thermostat to be about 60°C too hot, so the chance of having an accurate thermostat was really appealing.
To replace the element was a very quick job, but the thermostat was a lot more complicated, as I bough the cheap generic one rather than a like for like replacement. So the wiring guide was a little more complicated.
The upshot is that we now have a working oven with a thermostat accurate to about 5°C, what more could you ask for?