Privately owned. Not to be confused with the National Trust’s Canons Ashby.
I remember cycling to Castle Ashby some years ago, when I was younger and fitter, and entering the central courtyard. The house is no longer open to the public, but the gardens and church are regularly open.
The gardens are impressive, and include an area of formal gardens with an Orangery and other structures, an arboretum (woodland), and a walk past stretches of water. Adjacent to the gardens is the walled garden, laid to grass. It can be looked into but not entered, and the house’s terraced garden likewise can be looked into but not entered. There is a menagerie housing meerkats, monkeys, exotic birds, pigs, a giant tortoise and a miniature horse.
The church is normally open but I did not find the interior of especial interest.
The gardens are well worth a visit. Allow 2 to 3 hours.
Entry to the gardens is much cheaper in the winter months but some auxiliary facilities may be closed. Admission was by online booking only. If you need the loo on arrival, it is in the left hand end of the row of reception buildings (not well marked).