The current fan isn't quite big/powerful enough to keep the engine cool. By the time speed 2 comes on, it really struggles to keep the temp down. Instead, I've rigged up a switch as a temporary measure to run the fan at the more powerful fan speed when I'm going through town etc. It seems to do the trick for the time being.
However, today I forgot...
Anyway, drove back from work (25 miles). It doesn't appear to be blowing any steam out of the exhaust, oil cap appears fine. I'll check there's no oily bits in the coolant once it's a bit cooler.
Touch wood!