In comments on an earlier post, Cristiane asked if I'd seen the 1949 film version of Gigi. I hadn't, until I got the new DVD, where it's included as a supplement. (Unfortunately in a poor print with old subtitles that become unreadable at many points -- white subtitles on black-and-white film don't work once they've become faded.) Given the crappy print, it's hard to know how good it is, but Danièle Delorme is a wonderful Gigi. The director, Jacqueline Audry, was one of the first female directors of studio feature films in France (or, really, anywhere).
And having seen it, I now have the answer to a question I've had for a while: how did Alan Lerner manage to turn out a solid script for Gigi when so many of his other scripts had serious structure problems? The answer is that the script for the 1958 Gigi follows the 1949 version almost scene-for-scene. The character of Honoré appears to originate in this film (he's not in the Colette story), and many, many lines are taken by Lerner directly from the 1949 film script. Minnelli must have seen the 1949 movie too, because some of the camera setups and shots are pretty similar; even bits of business like Honoré's voice becoming nasal when his valet pinches his nose while shaving him.
Lerner did, in other words, what he did what he did with the 1938 Pygmalion movie: take an old movie script and lean on it for dear life. A smart move, because when he tried to write a script without that kind of support, he usually made a mess. (His script for the stage version of Brigadoon is good, but after that...)
There's nothing wrong with basing a musical on a non-musical movie script, of course; the unfortunate thing is that whereas Shaw got credit for My Fair Lady, the writer of the 1949 Gigi movie, Pierre Laroche, didn't get any credit on the musical remake. Not that this is Lerner's fault per se; it was standard policy on remakes to deny credit to everybody but the writer of the original source material, no matter how many scenes were taken from an intermediate version. So The King and I, stage and screen, is heavily based on the script of the 1946 film version, but the screenwriters got no credit (and presumably, no royalties) despite the use of some of their scenes and dialogue.
Update: Speaking of bad prints, this version of the 1958 Gigi is hardly a prize either -- it looks like some scenes are faded and washed-out. I guess it looks better than the previous DVD, but this movie obviously needs a lot of work done on it, and it hasn't been done here.