As mentioned above my car has started (after a good deal of churning) on every occasion, but a couple of times has either idled much too high, or has seemed to have a sticky throttle.

But I don't think this was a sticky throttle - I think it was the fuel injection system getting its knickers twisted. By turning off the engine, removing the key, waiting a few seconds and then re-starting the car using the usual procedures the normal idle speed resumed.

I have had something similar on my Aero 8 once - same procedure fixed it.

Could be completely wrong but these fuel injection systems do have all sorts of 'clever' features that might get confused by a bit of cold or a tiny bit of ice / water.