Eliza Doolittle was the most coveted role in a decade, and Audrey was desperate to have it, telling a reporter years earlier I'd do anything to play Eliza Doolittle in My Fair Lady. Agent Kurt Frings gave her the news over the telephone You've got My Fair Lady! Hepburn told Modern Screen magazine how she dragged her mother out of the shower in her haste to share the exciting news. Based on George Bernard Shaw's Pygmalion, Alan Jay Lerner and Frederick Loewe's musical adaptation opened on Broadway in 1956 with Julie Andrews as Eliza and Rex Harrison as Professor Henry Higgins, becoming one of the biggest hits in Broadway history and running for over six years. Warner Bros. won the screen rights for an unprecedented $5 million. It would be Jack Warner's swansong, with the largest production budget ever at that time.

Fans of the Broadway show clamoured for Julie Andrews to be cast in the lead, but she was an unknown in Hollywood and Warner wanted big name movie stars that would be known all over the world - he wanted Audrey Hepburn. Hepburn too felt that the role was Julie's, and was reticent at first, but when she saw that Warner would only offer the role to another star if she turned it down, she swiftly accepted, telling Barbara Walters years later I thought I was entitled to do it as much as the third girl. According to Andrews, Hepburn would say to her in later years You should have done My Fair Lady, Julie — but I didn't have the guts to turn it down. Many in the industry were outraged at Andrews being overlooked, so much so that Warner publicly justified his casting decision, stating With all her charm and ability, Julie Andrews is just a Broadway name... In my business, I have to know who brings people and their money to a theatre box-office. Cary Grant, Warner's first choice to play Higgins, responded There is only one man who could play this and that's Rex - so the part went to Harrison. Warner already had his big name to guarantee the success of the picture.

After weeks of rehearsals, lessons and fittings, filming began on the elaborate production in August, Audrey enduring hours in make up each day to be transformed into the grubby Covent Garden flower girl. No one had ever seen such dedication. From day one, Audrey had been determined to make it a success, announcing to Beaton and director George Cukor This picture is one we must all remember. Wonderful talents, everyone right, everyone happy. It's the high spot, let's enjoy it!