More What's My Line?

Here's a fascinating appearance on What's My Line?  It's with famed Broadway composers, Lerner & Loewe -- but they aren't Mystery Guests.  This comes in 1956, after My Fair Lady has opened, but they're still so unknown that they're just on as themselves.  They even sign in as themselves!  And it's not like this is their first musical.  They'd had two big hits previously -- Brigadoon and Paint Your Wagon.

Two other things are fun in the clip.  One is that David Niven is on the panel.  And the other is an incredibly rare terrible guess by Bennett Cerf, who's so certain he's right.

https://www.youtube.com/watch?v=T74qnT7WFZw