GavestonPS said: "Personally, I found the telecast of the show from the Drury Lane impossible to dislike! But I agree re the singing of Dorothy Brock's role. Download the cast album of the West End production: Sheena Easton sings the role in head voice and it's a revelation, not only lovely to the ear but dramatically useful in distinguishing between Brock (old school) and Peggy Sawyer (new generation)!
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As for Tammy Grimes, some performers' talents just don't transfer well to electronic media (be it film, videotape or recording). I worked with Tammy on a show called A MUSICAL JUBILEE, a Broadway revue that flopped and transferred directly to Fort Lauderdale when we lost the rights to PIPPIN.
Tammy was singing alongside "real" singers, including Patrice Munsel, Larry Kert and John Raitt, and I promise you she held her own through sheer star wattage. Her rendition of "I've Told Every Little Star" still haunts me (in a good way). (She was more than bit looney off-stage and we couldn't book the stars in our usual hotel because Tammy and her dog had destroyed a suite there and she was banned.)
She was a classic actor-who-sings-a-little a la Robert Preston, Rex Harrison and Barbara Harris. I agree with the poster above who wrote that musicals were far more interesting with such performers than today's shows in which everyone is trained the same and sounds alike."
Probably being churlish, but Barbare Harris had an excellent singing voice. Listen to the cast recordings of Apple Treeand On a Clear Day.