Debbie Reynolds: Alive & Fabulous

When the 78-year-old Debbie Reynolds totters onto the stage for her one-woman show, Alive and Fabulous, her parade of tunes and anecdotes seems destined to be filed under 'c' for car-crash – another celebrity who would be better off resting on her laurels than showing us how badly the leaves have withered.

The star of Singin’ in the Rain sways alarmingly and her diction is slurred. When she drawls through a self-referential song about her own life with the refrain “I'm Still Here”, it's easy to wish she was not here at all, but tucked away in some dignified Bel Air retirement.

But it gradually becomes apparent that, if this is a car crash, it's a knowing, controlled one. It doesn’t matter if she’s really sozzled – she doesn’t care who knows she likes a drink – or just putting it on. Either way, she is funny, self-deprecating, mischievous and utterly charming.

"You have no idea who I am, do you? Did you see Star Wars? I'm Princess Leia's mother," she tells the thirtysomethings in the front row, before playing us a show-reel of clips that make her daughter Carrie Fisher’s credits look like walk-ons. It's the persona we saw in Carrie's autobiographical Postcards From the Edge, and again in Will & Grace: the preening mother whose ditziness gets her away with murder.

Her jokes come with an ironic cymbal crash in case they're too cheesy – but in general they aren't. She offers a revealing DVD-style commentary to her show-reel – "Nobody looks down when we dance down those stairs, I don't know how we did that" – as well as obligatory cattiness about Carrie's father Eddie Fisher, who humiliated her by running off with Elizabeth Taylor.

But the evening really warms up when she reveals a wicked talent for mimicry: a rambling Jimmy Stewart; Bette Davis walking with her legs splayed open; and Marlene Dietrich singing “Falling in Love Again” in a voice like a waste-disposal unit. Then she disappears offstage and comes back in prosthetic nose and blonde wig to do the young Barbra Streisand. She looks like a geriatric Bo Selecta. It's plain that this once fresh-faced innocent is determined to grow old disgracefully, and it’s all rather surreal – in a good way.

A musical tribute to her friend Judy Garland seems like an error of judgement – "this is not meant to be an impression," she says, which is just as well – but turns into a tale about dropping round after work: "We'd put Lorna, Liza and Joey to bed, and then we'd have a coupla drinks, and then we'd give Liza a drink..." A piece of sentimental name-dropping has flipped into glint-eyed mischief. This is Joan Rivers in a twinkly granny's body – and all the more dangerous for it.

"I am certainly alive – do you think I may have been fabulous?" she asks coyly at the end. She gets the loud “yes” she wants, and she is undoubtedly compelling. Many old-timers trade on past glories, selling the chance to be in the presence of former greatness. There's nothing former about Reynolds – just a blissfully deranged dottiness that you're relieved not to be related to.

- Simon Edge