The long littleness of life … Larry Kert and Elaine Stritch in Company. Photograph: Associated Newspapers/Rex  It's the first stage Sondheim I see, and only the second professional stage musical, and it's the London production of Company. I'm kinda new in this world and not sure how much I get about the relationships onstage, other than that the characters are all seriously flaky and that Manhattan will always be beyond our ken, but then there's this woman, Joanne. The word is woman, she's already far from young, especially in style and attitude; she's not nervous, not placatory, not supplicatory, not appealing. Joanne is played by Elaine Stritch.  When the rest of the female cast call the fragile tenor lead "Bobby", or even "Bobby baby", she drawls his name "Robert", with a feral growl on the "R", and calls him "kiddo". She leads a throwaway number that fills in Joanne's alimonied backstory ("it's not so hard to be married … I've done it three or four times"), and from her vocal operating mode, she's a dame in the sense I'm coming to understand, and worship, from devout old-movie watching – there's something of Bette Davis, Rosalind Russell and Celeste Holm about her dry manner and wry delivery. (Turns out at one time and another, and the other was usually touring in stock, she played parts they'd premiered.)  Then Stritch's Joanne gets her solo, The Ladies Who Lunch, and it's terrifying. She hits the sustained blasts on the words "Everybody rise … rise", the awe-filled summons to toast those ladies, and it's impressive, but it's the calm way Stritch delivers the rest of Sondheim's summary of post-marital female decline, of the long littleness of life, that's a revelation.  So far, I've been under the happy illusion that dames are cool because they're rising above their knowledge of the truths that everyone else in the plot keeps ignoring. But I can hear in Stritch's delivery, in the hard burn of her notes, that – no matter how many vodka stingers she downs – her character can't escape failure, boredom and loss. So, I thought, you aren't born a dame; it takes bad experience, not just borne but wrought into humour, to become one. It's an earned honour. There should be a medal.  I'm scared about seeing Stritch live in tights in her mid-70s, despite all the intervening decades of listening to recordings of that voice whenever I could find them – often just fragments. (The enduring Sondheim stage-belter turned out not to be Stritch, but Angela Lansbury, who had started as a pixie vixen and expanded.) And then she stalks on stage, porting a chair with longer legs than her own, neglects to sit on it, and – first job of the dame – supplies us all with the backstory.  This time not a character's backstory, not the show's, but her own. One damn self-inflicted disaster after another – professional, emotional, romantic, alcoholic. The songs are veterans' numbers, Broadway Baby and I'm Still Here, from Follies, her voice of lived history has dropped from brass to woodwind, and mostly bassoons at that: her boom of a hoot on the line "Herbert and J Edgar Hoooooooover" in I'm Still Here gets a round of applause, as well as a laugh.  We're all waiting for her to reprise those Ladies, and then suddenly she detours into Coward's If Love Were All ("the most I've had's just a talent to amuse") sung as a hybrid with Gershwin's But Not for Me. So now we know – how much you have to give up, do without, to achieve damedom. You have to look loss in the eye and no, you don't get to sing soaring torch songs about it. And very eventually – where in hell does Stritch's energy come from? – she reaches the lunching ladies.  She knows it's the defining song of her life, the number in which Sondheim's fervent belief in not telling sweet musical lies (he loathes emotional dishonesty) melds with her fierceness in delivery. Way back when I heard her sing it first, she sang it angrily, especially the word "fools" and those iterations of "rise" (Listen to them preserved in the original cast album, Shiver). But in this performance, the song is an anthem of forgiveness. Whatever those ladies had been doing was just human, and she's tolerating it, wryly, dryly. The dame has forgiven everybody: she has forgiven herself.  • From Sondheim to 30 Rock: Stritch's career in clips• Stritch interview: 'I'm a do-it-myself kind of broad'• In pictures: an incorrigible scene-stealer
The Ladies Who Lunch was the defining song of Elaine Stritch's life. Veronica Horwell recalls two classic performances, delivered 30 years apart