Question...

I've never read of a specific reason, but Astaire tended to enjoy working with highly trained dancers, and Caron definitely was one.

This is pure speculation, but perhaps Astaire was also interested in Caron as a partner because of her height of just over 5'1". I once read that Mitzi Gaynor was considered for the role of Julie. She was the same height as Cyd Charisse (5'6"), and he had worried about appearing short beside Cyd (he was about 5'9", but his partners had a tendency to wear high heels--or even go up en pointe!). In fact, Comden and Green wrote this into the script of "The Band Wagon"--Tony Hunter keeps fretting that Gabrielle (Cyd Charisse) is too tall for him.

Anyway, Leslie Caron wasn't approaching his height even up on her toes, so that may have played a part in her appeal to him.

I hope it's not been too long since you posted your question about DADDY LONG LEGS .....

Leslie Caron had been hand-picked by Gene Kelly to come to Hollywood and film AN AMERICAN IN PARIS. She was in the French ballet and had done something or took some picture as a "cat." So Kelly was told about the "cat" woman. When he saw her, realized her manificent ballet skills, it was a done deal. But Caron herself did not want to make movies or go to Hollywood. It was Caron's mother who persuaded her to do so.

Once Caraon made such a huge impact in AN AMERICAN IN PARIS with Kelly (1951) at the same studio (MGM) as Astaire, I suppose Astaire couldn't wait to work with her. But there's another reason Astaire and Caron made the picture: the part of Julie Andre had to be a girl of about 18. That let out Cyd Charisse who would have been most likely. The other MGM female dancers: Jane Powell, Debbie Reynolds, Ann Miller would have never fit the bill. Caron just fulfilled all the requirements. And who else was French?

Dennis