According to PetulaClark.net, Pet appeared on “Captain Kangaroo” in 1976. I looked through a book about the program my sister Jeanie Beanie gave me for Christmas some years back, and I found this.
Petula was 43 in this picture, and looked 30, while Keeshan was only 48 or 49, but looked 65.
HA! It looks like Pet is about to marry the Captain. She is, of course, just beautiful. I don’t even remember that picture being in the book. What a find!