I thought I would repost both the clip (a current one) and the comment I made at the time.
Listening to it again - and keep in mind this was recorded in 1982, 10 years after their original performances - it is obvious that Johns was not a singer but ... and this is a very big but ... this is her song. She in-bodies first the bitterness then the regrets of love misplaced and finally the joy of love refound. Nobody did it better!
Saturday December 8, 1973 - Majestic Theater - A Little Night Music
It was a crowded weekend – Italiana with Marilyn Horne at the Opera Met, the Baroque Angel Christmas tree at the Museum Met, High Mass at St. Mary the Virgin (Smokey Mary’s), lunch at the Russian Tearoom, , non-stop activity – but suddenly that Saturday evening there came a grace note in both the musical and our weekend - a shared moment of melancholy quiet.
Glynis Johns sat motionless at stage left and in a voice that was never really meant to sing broke our hearts. Send In the Clowns had become popular in Judy Collins’ silken - almost sexless - version but here was the woman Sondheim had written it for, singing it the way he meant it to be sung. Singing of middle-aged love and the sadness of chances missed. And in the reprise with Len Cariou singing of the sweet foolishness and deep love that reunited them and would hold them together. It was a magical moment.
07 gennaio - San Raimondo di Peñafort