parents had grade 2 and that is much easier than 2*.
Everything had to be passed by the officer. Some things were nuts. eg, they were allowed to open up some decrepit rooms which had been partitione din the 60s and make them back into one big room, the new kitchen. Fine. BUT the place where the old passageway entered the kitchen ws red brick floor and the rest of the floor was old flagstones, as was the corridor outside. That patch of red brick had to stay.
Trouble was, the brick butted up against the flags, which were unevenly worn, so there was a bit that stuck up. After my mum had fallen flat on her face twice, they quietly removed the red brick and filled the gap with another flag. Looked loads better, much much safer, but the heritage person would have had a blue fit had he known.
He had a say over which paint, which colour pointing (looked rubbish) Insisted on old materials for some things where it was just a pain, and not visible.
It drove my parent's mad, and they were in principle in agreement with trying to retain and enhance the period features.
One thing that annoyed them was that it was falling down with the roof in dire need of replacement. Without my parents it would have rotted but they had very little say over what they could and couldn't do.