MikeF wrote: So it seems basically that parking is allowed anywhere it isn't "unreasonable". However I'm not sure what the legal definition of "unreasonable" is; it seems to be akin to "common sense" which often is anything but common sense. ...
Without trying to duck the issue, there's no hard-and-fast legal definition of "unreasonable" any more than there is of "unnecessary" which is the word used in the con and use regs. The necessity or reasonableness is a question of fact (rather than law) for the court to decide in an individual case. Decided cases ie the results of appeals to higher courts, resolve the law and the "facts" just give background material, but often open the floodgates that bit wider. Stopping to change a wheel with a punctured tyre would almost certainly be considered "necessary." Repairing cars in the street is probably unnecessary.
This thread is specifically about residential parking and the practical and political realities have to be considered. I don't know if a prosecution has ever been run on the sole basis that a resident was permanently parking outside their own house, but I've not heard of it (that's by no means conclusive.) If it's not happened in the past, I cannot see it happening now. Theoretically, if somebody has off-street parking available, it's hard to see how parking on the highway is necessary, especially if the resident parks there to prevent others from doing so, but who will do anything? It's a big tide to turn back. If things came to some sort of head in an individual case, I fancy that if the police resorted to fixed penalties which were not accepted, the CPS would be unlikely to prosecute: not in the public interest.
I can only remember one case of somebody insisting on "their right" to park outside their own house when things got to the point of tickets being issued - by one of the most experienced road traffic officers in Leeds at that time - and complaints being made (which is why I was eventually involved.) This was in a terraced street only a couple of streets from where I spent the first few years of my life. (Not legally a "fact" in the case BTW but when we lived there, nobody had a car.) The street in question was a cul-de-sac and the house was the last house before the wall across the end of the street. The problem was that at some stage, long before residents had cars, the entrance to a school had been created in the wall, but to the right edge of the street, so the vehicle in question completely blocked the entrance when parked. The school was a "special school" where many of the children arrived, of necessity, by taxi or local authority transport. That was all still on-the-boil when I retired, having recommended that prosecution was becoming the only solution, so I don't know how it was eventually resolved. I've looked at the streetview to illustrate the story but a new primary school has been built with the gate in the middle of the street so parking on either side will not block it.https://firstname.lastname@example.org ... 312!8i6656
More generally, legislation is the job of central govt., but implementation is for the police and local highway authorities. I've posted before that local councillors will not upset residents over parking (search term <white funk>) The police no longer prioritise "roads policing" and within that, parking is off the radar.