update, Ford are not keen to go down PCM root, not convinced. Electrian still has car and has been testing and monitoring it, seems the battery suffered a small voltage drop (it's a new battery from few weeks back when problem first occurred), he charged it up and the car starts fine and still starts now. Something is drawing a few extra volts, could be starter motor although fires up strong, alternator has been checked for output too, starter could be old and bit tighter. I suggested only thing same is left overnight and it won't start, three times now, so only change is that my car is alarmed and locked, could my Clifford be draining over time, guy who fitted it said no, drains less than a clock in car he immediately then said have you got correct battery on, I said hope so, he said if alternator is a smart charge one, very likely then the battery must be a Silver Calcium NOT a lead acid which will not work properly.
I've asked garage to check they said will do ?