It seems as though Vfrpilotpb hit the nail on the head and some of us may have been a little too quick to assume this helicopter owner's neighbours were being unreasonable.
I've now heard from two separate sources that he positioned his hangar on the part of his land furthest away from his own house and close to his neighbour's house - blocking his neighbours' view and keeping his own unobstructed.
When advised that this was inconsiderate and likely to cause problems, he took the view that it was his own land and he could do what he wanted regardless of what they thought.
I'm told his response was similar when advised to stop doing engine runs at night.
If it's true, he appears to have brought the trouble upon himself.
I'm told his helicopter has been u/s for some months - no doubt to the relief of his neighbours.