It will be interesting to see what will happen should this chap contest his ticket at the Magistrates Court. The word unattended is open to interpretation when a good solicitor gets on the case. I can only assume he returned back indoors while the car remained running in the street. This really is all down to the circumstances and detail of the incident and the view of the Magistrate(s) on the day.
The offence of 'quitting' means having the engine running without having a suitably qualified driver present inside the car so it seems to me that the offence is complete.
If people don't like the law, then they should lobby their MP to get it changed. I have to enforce laws that I don't agree with; that's what I'm paid for.
This bloke obviously tried to make the copper's job difficult, so the copper played the trump card and stuck him on. This bloke had a higher trump card when he went to the press; who really cares? It's £30, pay up and learn your lesson.
Haven't the press got something better to report?