I've walked past there, didn't realise whose it was but it stank of money!
The Telegraph makes a big thing about the permissive path, though, in a journalistic attempt to blacken the owners further. Pesonally I think they're good and I'm always happy to use them to preserve someone's privacy, for that's what they're usually for. There was one on a walk I did three weeks ago, in the same area funnily enough, it was clearly and politely signed at each end, with one arrow pointing towards the definitive path and one pointing towards the permissive route. I think only an obstinate person would insist on going the "proper" way.