After getting two punctures in a week in my rear tyre (after 3000 puncture-free miles), I swapped the front tyre, which still has a bit of life left in it, to the rear, and put the only spare I had to hand (a Michelin Service Course - wouldn't be my first choice at this time of year, but needs must) on the front. New GP 4 Seasons have been ordered, so this is just a temporary fix.