A wealthy landowner, he was the owner of Tye House, and had been married to Bella who was killed in a shooting accident almost two years prior to the events of the episode.
He was confined to a wheel chair and was engaged to be married to his former ward, Katherine Lacey. Unbeknownst to him, his sister-in-law, Phyllis Cadell, was completely enamored of him. After her sister's death she served as chatelaine, but said she would leave after the wedding.
As things transpired, it was revealed that Katherine, with the help of her brother Michael, had murdered Bella to clear the way for Katherine to marry Henry for his money. Barnaby also speculated that he wouldn't be surprised if they had started him on a terminal path already, "slow poisoning or something."