Depending on what newspaper you read Dawn French and Jennifer Saunders' current tour is either their last ever live tour, the last time they will perform together or possibly even the last time Dawn French will get up onstage before she retires to a quiet life eating Chocolate Oranges in the West Country.

The Evening Standard will be reviewing the show when it reaches the south of England later this month, but early reports from the northern leg of their first outing in seven years suggests that it is pretty good. At their advanced age they may not be winning over any new fans but they are certainly satisfying the ones they have with a mix of Madonna spoofs, Catherine Zeta-Jones send-ups and Abba songs.

I'm not even going to enter into a debate about whether women can be funny at this juncture (answer: yes, even though at a recent talent competition I was judging, when the second woman came onstage halfway through the show a man behind me said "Oh no, not another bloody woman"). What I'm interested in is the nature of double acts.

I guess the obvious comparison is with marriages. Some last longer than others and there are inevitably arguments. Sometimes the spark just goes. One performer I interviewed described a double act as "like a marriage but with less sex."

French and Saunders seem like a couple who have never had a cross word, yet even they have decided to, as it were, "see other people", ie pursue other projects. Maybe it runs in the family. A couple of years ago Ade Edmondson, aka Mr Saunders, decided to knock his slapstick double act with Rik Mayall on the head. Which was apt, because they'd been knocking each other on the head for years. They are still mates and may well still work together again, but don't hold your breath waiting for another series of Bottom.

Another intriguing case study is Vic and Bob. While they haven't actually split and last year did an enjoyably daft Radio 2 series together, Vic Reeves has frequently been working solo in recent years. But even as his most ardent fan I'd be hard-pushed to say that anything he has done without Bob Mortimer has come close to the giddy heights of their toweringly silly Big Night Out.

Of course, double acts will invariably want to try different things and you only live once, so who can blame them for branching out? It has happened with Peter Cook and Dudley Moore, Baddiel and Newman and pretty much any double act you can think of. In fact Morecambe and Wise might be the only high profile duo whose career together ended due to death.