Comedy: French & Saunders, Palace Theatre, Manchester

Thirty years after Dawn French and Jennifer Saunders teamed up at drama school, and more than 20 years since their first TV series, this tour is billed as the double act's final outing. They'll still work together – they're both in Saunders' WI sitcom, Jam & Jerusalem, for instance – but no longer as a sketch duo, which makes this quite a momentous occasion. For sheer longevity, as well as for their love of celebrity guests, film and music pastiches, and riffs on their own friendship, there's no comedy partnership to compare, male or female, apart from Morecambe and Wise.

They've amassed plenty of classic material, too. On their farewell tour, they mix new sketches with oldies, and the format doesn't get much funnier than the very early skit of French as a teenager, fumbling through an explanation of the facts of life ("First you get lots of towels and spread them out on the parents' bed ..."), nor does it get much more piquant than the vignette about two rich girls who spend so much time at boarding school that they've never met their families.

And then there's the sketch that was the seed of Absolutely Fabulous, with French in the Saffy role. What's amazing is that the monstrous Edina is already fully formed: everything that would go into the series is there in those few minutes. You can't watch it on stage without seeing Saunders as a leading satirical playwright who happens to specialise in bite-sized playlets.

Still, the show isn't quite the spectacular, guest-starry send-off it could have been. There's a bit too much reliance on filmed segments projected on to a big screen, and for every perfect sketch there's a self-indulgent interlude of them bickering over whose career is better, or a showbiz parody that begins and ends with one of them clomping around the set dressed as Madonna. But even these rough edges are part of their charm at a time when so many younger comedians are putting on big-budget stadium gigs for catchphrase-chanting crowds.

Whether or not you're a fan, there's always a sense that French and Saunders are two mischievous buddies who muck about for their own amusement, and have somehow sneaked their private jokes into the mainstream without com-promising. Tonight, there's never a dip in their buoyant energy, infectious chemistry, or willingness to be rude, silly and childish: they're both wearing voluminous trousers that belt up above the bust line, making French look like a Teletubby.

After all these years, they perform with all the verve and unselfconscious playfulness of students making their Edinburgh Fringe debut in a tiny venue and hoping to be reviewed as the new French and Saunders. The show might be hit and miss, but over three decades it's remarkable how consistent its stars have been.

Nationwide, to 5 May; see frenchandsaunders.com