Annoyed by new neighbour's lack of respect for the street

Send an anomous letter to the council. Likely nobody in enforcement yet knows about it.

A door requires a carpark?

Council won't act on anonymity.

What sort of house is it, Is it attached or are they independent of other homes?

Correct, those days are long gone, in fact local authorities have introduced quite stringent procedures in relation to reporting alledged unauthorised developments which absolutely require the persons reporting, Details, Address and contact information. My own lists quite clearly what is required and go further by saying they will not investigate reports without full contact details of the person reporting.

This said, local authority will not disclose any information of those making a complaint.

I'm assuming this approach to weed out spurious complaints.

Altering a public path is a definite no. Just submit the letter.

You wouldn't want someone to trip up on said path and get an injury which could lead to a claim. I doubt they have even considered that.

It's not just the front door. There are multiple requirements for making 2 separate properties like fire separation. Utilities etc.

Another reason the council won't entertain anonymous reports is if it eventually goes to court.

while a complainant's  name won't be revealed, information can be sought under FOI Act and whilst details will be redacted, it's a process of elimination as to who reported the breach.

Enforcement not endowment.

I completely agree , I can't comment on the rights and wrongs of local authorities introducing stringent reporting guidelines but clearly there was a lot of spurious and unsubstantiated complaints being lodged, clogging up planning departments.

I can say, right across the road from me a 70's style bungalow has just been tripled in size and roof raised by 10 feet. Absolutely no planning Lodge (confirmed) , I believe reports lodged and its a very proactive local authority. Will anything be done, that's an open question, personally I feel the restoration looks excellent, does this mean it's acceptable without planning, No but like yourself, I'm not getting involved ,it's a very rural location. If a local Authority can't see an unauthorised development like this and not ask questions, there is seriously something wrong (the property in full view from a main road )

You said you're annoyed they were allowed to do this, but that they didn't get permission. Which is it? I'm guessing they weren't actually allowed. In which case council probably don't know yet.

Not sure why you mention garage. But you're mistaken, you don't need permission to convert a garage subject to reasonable comditions

Nonsense. That applies where they have to investigate on private property. If council know it is unauthorised, they have act on it. They don't need anyone to assign an complaint to. It's unauthorised development, if they know it happened, its literally their job to get involved. They can commence enforcement on their own.

If you're aren't going to let council know about it. Then you can't complain that they didn't do anything.

None of those issues you mentioned have anything to do with the planning department.

All planning permission involved private property. That's not relevant at all. The vast majority major enforcement actions have been the council acting themselves. By the logic above, a group of neighbors could all collectively agree to build without planning and not complained on each other to evade the process. Good luck with that.As for how who the could know. A simple photograph of the street would show the unauthorized development in progress, at that point it's black and white. There is is no hearsay, their is a publicly accessible record of planning. A planner could confirm in seconds. There is no grey area.

What you are thinking of is where somebody had permission to build 20 feet high, and a neighbour says they build 22 feet. Or they are building an exempt development, an a neighbour claims the area is too high. In that cases you can't tell from a photo, it's entirely in a grey area. They they need to investigate and take measurements. And they want a name in order to avoid people making spurious claims in order to "check" the neighbours work.

Not an architect or anything but I was looking at converting a garage but it was more complex than that. It was converting a garage into a one bedroom apartment and building over it. I was told I would need planning permission for that. In the end there were very deep flaws in the house and we abandoned the purchase. Open to correction here.