When the Boat Comes In S03E01 - A House Divided

Matt and Tom rescue the injured Jack from the ruins of Mandrake Place. Arthur is appalled by the destruction and contacts the Association for the Preservation of Great Houses. Its Chairman, James Channing, threatens to prosecute. Jessie warns Jack and offers him an alibi. Jack learns from Caroline that her brother-in-law, Roddy, and Channing have been lovers. To Caroline's disgust he says he will use this to blackmail Roddy into persuading Channing drop the prosecution.