Having seen Death on the Nile for many times, it only occured to me recently that the role of Colonel Race, played by David Niven, doesn't seem to serve much more than being a slightly more "socially competent" assistent to Poirot, while all the other characters are more or less suspects in the murder of Linnet Ridgeway. Therefore I came up with the (maybe a bit far-fetched) theory that his character might just have been added to the movie in order to give Poirot, who might seem a bit "remote" at times, a charming British counter-part to work with (given that it also was the first of the Ustinov-Poirot-movies).
So first of all, is this character also part of Agatha Christie's novel the movie is based upon and does the movie deviate in his depiction in any way? If yes, then is there any information about the reasons for this deviation from the novel? (Of course it might be that I'm entirely making up things here.)