Went out to car this morning and it started just fine,drove about 4mls and parked up,went shopping for an hour or so got back to car and although it turned over well enough it wouldn't start.After a further quarter hour or so it started up as though nothing had happened,then drove about another10 mls and parked up waiting for the dragonlady for a couple of hours,car was then very difficult to start but eventually did and ran fine for about another 3mls when it just died[on a very busy roundabout too!]managed to coast it off roundabout and called AA.He didn't even bother to look at it[although in fairness we were in a fairly precarious place to be fixing a car]and towed us the couple of miles to home.Am I right in thinking crank sensor?As long as weather is o.k. tomorrow I might change it anyway as I've got a spare in the glovebox[seemed to be advised on here to carry one so I did!]