score:6
Because there was no need to. During the English Civil War, the old Wardour Castle was besieged and largely blown up by the 3rd Baron Arundell. This is not readily apparent from the Wikipedia article, which depicts this photo:
(Photo by Simon Burchell CC BY_SA 3.0)
Well, that seems formidable enough. However - if you walk around the castle, you'll see this:
Photo by Mystery Cat CC BY_SA 3.0
As you can see, that's pretty much a ruin. There was no need for Parliament to order it slighted because it was already essentially demolished by the fighting. When the Arundell family recovered in fortunes, they ended up building a new castle altogether.