Permitted dev ground levels

On another forum, someone has posted a moan about his neighbour's extension.

The gist is that he thinks it is too high, and the council say that there is no problem because the original ground level on the neighbour's side is higher. He thinks that this is a special local rule and complains that as we live in a hilly valley it makes a mockery of the rules

Am I correct in thinking that nationallly it normally takes original ground level where the build will take place? To me that's the common sense attitude. Otherwise those terraces that you see on hills going upwards with the street would get progressively smaller?

The height is measured from the highest natural ground level that the development is built immediately adjacent to. It's national and defined in the technical guidance.

Thanks - that's what I thought.
he seemed to think that this was a local "problem"

To me, it makes sense to regard the original ground level of the plot to be the datum line.

I know which other forum you are on...I think he determines the problem as being exasperated locally because of the rolling nature of the area. There has to be a national definition, because he is on lower ground he fall foul of it.

Yup!