The Prince and the Showgirl (1957)
The Prince and the Showgirl is a 1957 British-American Technicolor romantic comedy film produced at Pinewood Studios starring Marilyn Monroe and co-starring Laurence Olivier who also served as director and producer. Filmed in conjunction with Marilyn Monroe Productions, it was written by Terence Rattigan who based the screenplay on his stage play The Sleeping Prince.
More at Wikipedia.