Which author co-wrote the screen play "Chitty Chitty Bang Bang" loosely based on an Ian Fleming novel?

"Chitty Chitty Bang Bang" is a 1968 musical adventure fantasy film, directed by Ken Hughes with a screenplay co-written by Roald Dahl and Hughes, loosely based on Ian Fleming's novel "Chitty-Chitty-Bang-Bang: The Magical Car" (1964). The film stars Dick Van Dyke, Sally Ann Howes, Adrian Hall, Heather Ripley, Lionel Jeffries, James Robertson Justice, Robert Helpmann, and Gert Fröbe.

The film was produced by Albert R. Broccoli. John Stears supervised the special effects. Irwin Kostal supervised and conducted the music, while the musical numbers, written by Richard M. and Robert B. Sherman, were staged by Marc Breaux and Dee Dee Wood. The song "Chitty Chitty Bang Bang" was nominated for an Academy Award.

Roald Dahl (13 September 1916 – 23 November 1990) was born in Wales to Norwegian immigrant parents. He served in the Royal Air Force during the Second World War. He became a fighter ace, scoring 5 confirmed victories, and, subsequently, an intelligence officer, rising to the rank of acting wing commander. He rose to prominence as a writer in the 1940s with works for children and for adults, and he became one of the world's best-selling authors, having sold more than 250 million copies worldwide.