In the stage adaptation Murder on the Nile, Canon Ambrose Pennyfather is an elderly passenger on the Lotus on its cruise down the Nile. He is the best friend of the late father of Kay Ridgeway-Mostyn, and took charge of his estate after his death. He became the guardian of Kay and managed her financial affairs until such time as she turns 25, or she gets married. After the murder of Kay the captain of the boat asks the canon to investigate the case pending the arrival of the police. In this respect the canon is an amalgamation of the roles of Andrew Pennington and Poirot. When Agatha Christie wrote this play from her novel she planned for her friend Francis L. Sullivan to star in it but she was "tired of Poirot" and so created this character for Sullivan.
The Canon differs from Andrew Pennington in that there is not much of a hint of wrongdoing in his management of Kay's financial affairs. He does admit to William Smith that when he read about Kay's wedding to Simon Mostyn he rushed down to Egypt and and pretended to meet Kay by coincidence but he claims that this was to look after her. Stage directions directions do indicate that there is a touch of fanaticism about him in respect to charitable works and he does ask for money occasionally for such projects but since this depends on Kay being alive there is not much of a motive for him in wanting her death.