I've had codes read (thanks Alex) and the key one is obviously the idle speed control - signal too high.
Now what happened next - Alex cleared the codes and then I tried to restart the car but the battery had gone flat, so we started it from his Volvo. Lo and behold on driving home the idle was normal and has stayed so.
So either it was some magic with Vida, the flat battery, or a combination that has so far fixed it...
Nothing usually simple with these cars.
