I visited Luton Hoo when it first opened. Part of the course is within the historic park, which was designed by Capability Brown and is very heavily protected; consequently earthworks were strictly limited; essentially they were allowed to build greens and tees only. Most of the course is on former farmland outside the park, but to keep it consistent with the park holes, they decided to make the whole course bunker less. I didn't think it was desperately interesting.
The hotel in the grand old house is astoundingly opulent. The house was built in the eighteenth century for the Earl of Bute, Prime Minister for a short time between 1762-63. In the early twentieth century, it was bought by Sir Julius Wehrner, a diamond dealer. His son Sir Harold, who inherited it from him, was married to a woman who was the daughter of an exiled Russian Grand Duke; consequently a very OTT Russian Orthodox chapel was built in the house.
I think any golf course improvements will have to deal with the same restrictions on work in the historic park as the original course. Could be a tricky one.
(Edited to add): Looking at the planning documents (an EGD project, obviously for anyone with serious Ryder Cup ambitions) the proposed new course would appear not to touch the historic park. A good decision, I think.