I'd like to think that the police, if any miraculously appear , would take a reasonable view .But traffic enforcement is increasingly delegated to local authorities . Either wardens , some of who can be 'little Hitlers ' .How easy is it to find suitable staff, prepared to walk around in all weathers, and take abuse on minimal wages. It will attract those who enjoy the confrontation and feeling of power but lack judgement. Also enforcement can be from traffic camera images, which dont always tell the full circumstances , and administered by staff for whom issuing penalty notices is merely a mindless routine. Cameras could certainly pick up drivers in traffic using a phone, but not necessarily that a properly parked car has its ignition on.
My advice is if a little Adolf appears, be polite , and if a penalty is unfairly issued, take photos of the full situation,dont ignore the penalty, but plead not guilty in good time.