Posting this from the hard shoulder of the M4!
Driving along and the car starts juddering, with revs dropping. Pulled in and it is ticking over badly so decide to turn it and restart. The car catches and runs for a couple of seconds before cutting out. Now it doesn't even have enough power to keep the hazards flashing! Alternator? Something else?

The AA are on the way so typing to keep my fingers warm if nothing else!!!