The building used for Agatha Christie’s house in the Doctor Who episode “The Unicorn and the Wasp” is Llansannor Court. Another nice movie fact is that the father of David Tennant (the Tenth Doctor) has a very small cameo appearance in this episode. Also, Felicity Jones stars in this episode. Much later she will play a much larger part, Jyn Erso in “Rogue One”. An episode to watch, for sure.
Again an episode with the Tenth Doctor, David Tennant, The Unicorn and the Wasp. Agatha Christie’s mansion is is fact Hensol Castle.
The same location was used in various episodes of ” The Sarah Jane Adventures” (Last of the Sontaran).