In 1966, Desi Arnaz was still trying to reclaim a foothold in the TV sitcom biz, mostly with pilots written by Madelyn Davis and Bob Carroll, Jr., who had served him well on I Love Lucy and The Lucy Show among other programs. This pilot is for The Carol Channing Show, which also starred Richard Deacon (fresh off The Dick Van Dyke Show) and Jane Dulo. Also present in the cast was Jimmy Garrett, who had been on The Lucy Show and there's a moment in there where Richard Deacon impersonates Channing and sounds like he's dubbed by June Foray.
Arnaz produced and directed and one presumes it was Ms. Channing who persuaded Jerry Herman to write the theme song. I have no idea when this pilot was filmed but she left Hello, Dolly! on Broadway in August of 1965. I also have no idea if or when it aired but this film runs 37 minutes without commercials so if it was broadcast, it was probably chopped down a lot. It was not unprecedented for producers to deliver an overlong pilot as a selling tool.
This one didn't go but the next year, Desi, Madelyn and Bob got luckier with The Mothers-In-Law, which ran two seasons, the second of which featured Richard Deacon. Mr. Deacon was not out of work a lot…