In the novel Death on the Nile, Mr Ferguson (actually Lord Dawlish) is a young aristocrat, who became a communist while at Oxford. He fell in love with Cornelia Robson and proposed to her, but she turned him down.
Mr Ferguson is described as a "tall, dark-haired young man, with a thin face and a pugnacious chin".
Mr Ferguson says that there are a lot of people on the Karnak he would say the world could do without. He mentions Linnet Doyle as an example, saying that there are hundreds and thousands of "wretched workers slaving for a mere pittance to keep her in silk stockings and useless luxuries". He says that he has heard that Linnet is one of the richest women in England, and has never done any work in her life. When Poirot asks who told him this, he says it was a man who worked with his hands, and was not ashamed of it.
Poirot observes that Mr Ferguson has a passion for violence, as he says that the "dressed-up, foppish good-for-nothings" ought to be shot. Mr Ferguson says that one has to break down and destroy before one can build up.
Mr Ferguson tells Poirot that he is in Egypt "studying conditions". He does not elaborate on what these conditions are.
Mr Ferguson asks Cornelia Robson why she allows Miss Van Schuyler to bully her, and tries to convince her that everyone is born free and equal. She says that they are not, and mentions that she would have liked to be born elegant and beautiful like Linnet, but she was not. Mr Ferguson says that Linnet ought to be shot as an example. He also tells Cornelia that she is the nicest person on the boat.
When Poirot and Colonel Race interview Mr Ferguson, Poirot asks if it was Fleetwood who told him that Linnet was one of the richest women in England. When he is told that Fleetwood had a motive for killing Linnet, he becomes angry, and says that if they try to "saddle Fleetwood with this business", they will have him to deal with.
After the deaths of Louise Bourget and Salome Otterbourne, Cornelia says that the trip has been like living in a nightmare, with three deaths occurring. Mr Ferguson tells her that it is the future that matters, not the past, and that no one really cares whether Linnet, Louise, and Mrs Otterbourne are dead or not.
Mr Ferguson tells Poirot that Cornelia's father was practically ruined by Linnet's father, Melhuish Ridgeway, but Cornelia did not bear a grudge against her. He then tells Cornelia that she is the only nice woman he has ever come across, and asks her to marry him. Cornelia turns him down, saying that he is not serious, because he laughs at serious things like education, culture, and death, and so he would not be reliable.
Mr Ferguson tells Miss Van Schuyler that he wants to marry Cornelia, and that he will go on asking her until she accepts. Miss Van Schuyler tells him that she will take steps to ensure that Cornelia is not subjected to such persecution, and that he is not good enough for Cornelia, because he is of poor social position.
At the end of the novel, Cornelia reveals that Dr Bessner has asked her to marry him, and she has accepted. Mr Ferguson cannot believe that she would rather marry Dr Bessner than him. Poirot tells him that Cornelia is a woman of original mind, and it is probably the first time Mr Ferguson has met one.
At the very end of the novel, Mr Ferguson is in Luxor, and is once more telling people that it is not the past that matters, but the future.
In the 1978 Ustinov film adaptation, Ferguson is given the first name "Jim". This first name is a nod to the character of James Fanthorp who is not cast in the adaptation. Ferguson takes over Fanthorp's role of being called to the scene after Simon Doyle is shot and helping Dr Bessner move Simon to the doctor's room. As Cornelia Robson is not cast either so he is portrayed as expressing an interest in Rosalie Otterbourne and they end up becoming engaged. Bessner did not compete with Ferguson for her in this adaptation. Ferguson is portrayed by Jon Finch. Here he also has communist ideas but there is no mention of having been to Oxford or that he is in reality Lord Dawlish.
In the 2004 Suchet film adaptation, Ferguson was portrayed by Alastair Mackenzie. Like in the novel, he has what Poirot calls "progressive views". In this adaptation, just as in the 1978 version, Ferguson takes over part of the role of Fanthorp who is not cast. After Simon is shot, he and Cornelia Robson help Jacky to her cabin. He then summons Dr Bessner and he helps the doctor with Simon, although, compared to the 1978 version he is not as "hopeless" and afraid of blood. Like in the book, Ferguson also asks Cornelia Robson to marry him. In this adaptation, Poirot does reveal to Cornelia's cousin Miss Van Schuyler that he is Lord Dawlish but this doesn't stop Cornelia from turning him down. At the end of the show, Poirot commiserates with Ferguson. Ferguson says he really thought he had struck gold with Cornelia but it seemed he simply was not very experienced in such matters. Poirot tells him sympathetically that it happens more often that he thinks.