The Ash Tree (TV)

An episode in the BBC's annual A Ghost Story for Christmas strand. After taking up his inheritance, Sir Richard Dickin is haunted by dreams of his ancestor Sir Matthew Dickin who condemned a local woman to death as a witch. Before dying, the woman cursed the Dickin family and when animals on Sir Richard's estate start to die mysteriously, it seems the curse may be about to visit him. Put what part does the ash tree outside the mansion play in all this, and what horrors are lurking with its branches?