Complex sentence: A walled cottage garden of approximately half a hectare lies to the north of the house, and is divided into a several sub plots, each with their own identity; it has been maintained by the Countess of Chichester since 1966.
Split into simpler sentences: A walled cottage garden lies roughly half a hectare to the north of the house, which is divided into a several sub plots, each with their own identity. The walled garden has been maintained by the Countess of Chichester since 1966.