Flew to shoreham one cold winters sunday to meet a friend for lunch. Left it a bit late to leave for home and of course when we tried to start the aeroplane, no joy. After a lot of cranking, the battery was starting to wind down, so we started looking into trains and hire cars. Got on the phone to our maintenance place (luckily there was someone there as it was sunday) and they suggested the impusle spring in the newly overhauld mag. After a bit of messing around, turning the prop backwards and listening for the click, tapping with a hammer etc..., it was now under an hour till sunset and more than an hours flight with no runway lights back home. I gave it one final sloooowww crank, and bugger me but it started, so the others jumped in and we "expidited" our departure. Had to giggle, the tower man said "are you going to make it?" (meaning before it was dark) and my buddy replied "hope so" and off we went. Firewalled the throttle, GPS direct straight line all the way home and arrived in the twilight gloom.