First a Girl (1935)
Musicals in the 1930s were stiff mash-ups of song and dance numbers until the geometric fantasies of Busby Berkeley and then the narrative Fred Astaire movies, both in beginning in 1933 and 1934. This is a weird 1935 British affair that's well-enough filmed to remind you of Berkeley but is tepid by comparison. And as for plot, it takes awhile to get to that, following some decent and sometimes almost surreal dance/fashion scenes.
This is, in short, the original movie version of "Victor/Victoria." Once you get into the story, which will still be interrupted by old-fashioned feeling dance numbers, you'll get the cross-dressing stuff. All in fun. The leading woman (who does the switching, just as Julie Andrews did in the famous remake) is Jessie Matthews, who is a sort of Ginger Rogers type with a doll face. It's the doll face, highly feminine, that removes some of the credibility of the story--she does look slightly like a boy, when dressed as a man, but it doesn't quite carry. And of course, the point is to fool at least the other characters. The leading man Victor, played by Sonnie Hale, is also a problem, at least for audiences today, because he lacks charm, or sincerity, or pathos, or whatever might carry him through along with Matthews. He is meant to be the set-up for what "Victoria" has to do. But he's usually too dull for his own good, or he tries too hard. Matthews, at least, is purely charming and delightful. By the final number, however, when the tables are turned once again, Victor comes into his own. You might see it coming, but then it's divine.
It gives nothing away to say that the changing identities ruse is eventually suspected and the tension then begins. It's all done with a bit of stiffness, and filmed with uniform bright intensity, which makes it all a bit superficial, but is still enjoyable.