And here's another number from that London production of 42nd Street. In it, you can briefly see the characters of Maggie Jones and Bert Barry, who wrote the musical being produced, Pretty Lady, and who also play character roles in it. Maggie sings the lead on "Shuffle Off to Buffalo" in the second act and they both pop up in other numbers.
I remember when I first saw the show, it seemed like they were based loosely on Betty Comden and Adolph Green, who wrote a lot of musicals and also appeared sometimes in them. And in the four or five times I've seen this show staged since then, it always struck me that the folks playing Maggie and Bert were kinda playing Sally Rogers and Buddy Sorrell…