I've always been more interested in the making of GWTW and that era of Hollywood history than the actual movie itself. I saw the TV movie "The Scarlett O'Hara War" more than a decade after it first aired in 1980. You can find it on YouTube. It starred Tony Curtis as David O. Selznick as he searches for the right actress to play Scarlett. All the leading ladies of the day Joan Crawford, Carole Lombard, Jean Arthur, Katherine Hepburn, Talullah Bankhead, Miriam Hopkins vie for the coveted role. Selznick goes through many trials and tribulations trying to find the right actress. Finally at the end of the movie just as they begin production by filming the burning of Atlanta first, Selznick's brother introduces him to a young actress from England by saying "Meet Scarlet O'Hara." and it's Vivian Leigh(played by Morgan Brittany) and Selznick smiles.
Leigh was the perfect choice not just because she was so startingly beautiful(especially for the then new technicolor with those green eyes), but also half Irish and grew up in India during the British Raj, so acting like a member of a more privileged class and race wouldn't have been hard.