I was browsing on YouTube when by chance I saw something that caught my eye and decided to check it out. It's a 6-1/2 minute video of Julie Andrews and Mama Cass Elliot singing a medley of songs by Paul Simon. As far as I can tell, this comes from The Julie Andrews Hour in 1972.
Though both women had incredible singing voices, this doesn't necessarily seem a match made in heaven. Their styles were very different -- one of them meticulous and angelic, the other a more free-spirited Earth Mother. And Julie Andrews was hardly known for pop-folk '60s music. But they bring out the best in the other here, and it's a spectacular duet.
I think that if Julie Andrews had done this medley alone, it wouldn't have worked nearly as well, and arguably not at all. It might have come across as too precious, almost like when many opera singers try to sing pop. But Cass Elliot grounds the performance, and Andrews blends with her. And if Mama Cass did the number alone, it would have be appropriate and come across as fine, though no more than that. A nice Mama Cass Elliott tribute to Paul Simon. But with Julie Andrews' elegance and soaring soprano, it turns a standard medley into something with grace and richness.
I don't want to overpraise this, but along with a wonderful, full-orchestra arrangement (which could have gone way-wrong as well for songs written with a single guitar in mind), this medley from these two women is just a gem.