In the novel After the Funeral, Leo Abernethie was the second child of Cornelius Abernethie, younger brother of Richard Abernethie and husband of Helen Abernethie. Like his elder brother Richard and all the younger siblings, Leo had grown up at the family estate Enderby Hall. Although he moved out after his marriage, he and Helen were the only relatives to visit Richard occasionally. According to the family solicitor Mr Entwhistle, Leo was Richard's favourite brother. Leo was already deceased by the time of the events in the book. He and Helen had no children.
The Abernethie family tree is simplified and abbreviated in the ITV TV adaptation but Leo and Helen's branch is still represented. Leo is mentioned but does not appear on screen as he is already dead by the time of the events in the plot. However, in this adaptation, Leo and Helen have a son, George, who in the original is a son from the branch of Laura Crossfield née Abernethie and her husband Rex Crossfield. In the original novel, Leo is the second eldest after Richard. In the adaptation, Entwhistle tells Poirot that he is Richard's youngest brother.