Colonel Arbuthnot

Colonel John Arbuthnot is a passenger on the Orient Express in Agatha Christie's Murder on the Orient Express (1934). He was Colonel Armstrong's English best friend and is in love with the governess Mary Debenham; before boarding, Poirot overhears a conversation between the two. During the investigation Arbuthnot remarks that Cassetti should have been convicted at a second trial rather than murdered, and it emerges that he is on the train on Debenham's behalf and his own, as a personal friend of Colonel Armstrong.