Question: Upon whose novel was the 2006 historical drama film, in which Cleopatra Koheirwe played her first onscreen role, based?

Context paragraphs:
The Seventh Victim: The Seventh Victim is a 1943 American horror film noir directed by Mark Robson and starring Tom Conway, Jean Brooks, Isabel Jewell, Kim Hunter, and Hugh Beaumont.  Written by DeWitt Bodeen and Charles O'Neal, and produced by Val Lewton for RKO Radio Pictures, the film focuses on a young woman who stumbles on an underground cult of devil worshippers in Greenwich Village, New York City, while searching for her missing sister.  It marks Robson's directorial debut and was Hunter's first onscreen role.

Cleopatra Koheirwe: Cleopatra Koheirwe is a Ugandan actress, writer, singer and media personality currently working at Radiocity 97Fm.  Her first onscreen role was on "The Last King of Scotland" as Joy and she has since garnered numerous roles on different film and television projects locally and internationally including a role on Netflix's "Sense8" as Mother in season 2.

Cleopatra (1963 film): Cleopatra is a 1963 American epic historical drama film chronicling the struggles of Cleopatra VII, the young Queen of Egypt, to resist the imperial ambitions of Rome.  It was directed by Joseph L. Mankiewicz and shot in the 70 mm Todd-AO format, with a screenplay adapted by Mankiewicz, Ranald MacDougall and Sidney Buchman from a book by Carlo Maria Franzero.  The film stars Elizabeth Taylor, Richard Burton, Rex Harrison, Roddy McDowall, and Martin Landau.

The Last King of Scotland (film): The Last King of Scotland is a 2006 historical drama film based on Giles Foden's novel "The Last King of Scotland" (1998), adapted by screenwriters Peter Morgan and Jeremy Brock, and directed by Kevin Macdonald.  The film was a co-production between companies from the United Kingdom and Germany.

Ralph Richeson: Ralph Richeson (July 6, 1952 – October 27, 2015) was an American actor and painter best known for his role of Richardson, the fictional Grand Central Hotel's disheveled, eccentric cook on the HBO television series, "Deadwood".  Richeson was originally an extra on "Deadwood", before the show's producer, David Milch, noticed him and gave him one line, which became Richeson's first onscreen credit.  This led to Richeson's recurring role as the cook in 20 episodes of "Deadwood".  The series aired on HBO for three seasons from 2004 to 2006.

Marie Antoinette (2006 film): Marie Antoinette is a 2006 historical drama film, written and directed by Sofia Coppola and starring Kirsten Dunst.  It is based on the life of Queen Marie Antoinette in the years leading up to the French Revolution.  It won the Academy Award for Best Costume Design.  It was released in the United States on October 20, 2006, by Columbia Pictures.

Casino Royale (Climax!): "Casino Royale" is a live 1954 television adaptation of the novel of the same name by Ian Fleming.  An episode of the dramatic anthology series "Climax! ", the show is the first screen adaptation of a James Bond novel and stars Barry Nelson, Peter Lorre, and Linda Christian.  Though this marks the first onscreen appearance of the secret agent, Nelson's Bond is played as an American spy with "Combined Intelligence Agency" and is referred to as "Jimmy" by several characters.

The House Without a Key (serial): The House Without a Key is a 1926 American mystery film serial directed by Spencer Gordon Bennet.  It is based on the novel of the same name and is the first onscreen appearance of the fictional detective Charlie Chan, although the main stars are Allene Ray and Walter Miller.  The film is now considered to be lost.

The Auction Block (1917 film): The Auction Block is a 1917 American silent drama film directed by Laurence Trimble and starring Rubye De Remer.  The film was produced by Rex Beach, upon whose novel, "The Auction Block", the film is based.  It is not known whether the film currently survives.

Cleopatra (1917 film): Cleopatra (1917) was an American silent historical drama film based on H. Rider Haggard's 1889 novel "Cleopatra" and the plays "Cleopatre" by Émile Moreau and Victorien Sardou and "Antony and Cleopatra" by William Shakespeare.  The film starred Theda Bara in the title role, Fritz Leiber, Sr. as Julius Caesar, and Thurston Hall as Mark Antony.  The film is now considered lost, with only fragments surviving.

Supporting paragraphs: Cleopatra Koheirwe The Last King of Scotland (film)
Answer: Giles Foden