What house was used on location for 'Ham Spray'?

The house where they are all living together, and there is the scene where Carrington stands outside in the garden and see various bedroom windows lit up, and people getting off with each other inside.

I've just been to a country house in Sussex that looks so similar, I could swear that was it.

I don't think it was filmed at the real Ham Spray, as pictures I've looked at on-line don't look like the house in the film.

Any ideas?