Hard on the heels of the Charlton Heston fiasco, Love Letters, comes another epistolary romance. Hurrah for the invention of the email - it will save theatregoers a century hence from spending too many evenings in the dark watching elderly actors who prefer to do their work sitting down.

Fortunately, in this instance the protagonists - Gustave Flaubert and George Sand - are of some interest, and the actors, Peter Eyre and Irene Worth, can not only act but are also prepared to put some effort into it.

Sand, "the mother of French literature", was in her 60s when she wrote a spirited defence of Flaubert's widely panned novel Salammbo. It was to initiate a friendship and correspondence that lasted until Sand's death in 1876. During that time they seldom met, but they wrote so regularly and were so revealing about their differing attitudes to life and art that you wonder they had the time to knock off a few novels.

Flaubert and Sand were such opposites that it seems likely that if they had spent any extended time together they would have come to blows. But the safety net of distance ensured an intense affection. Played by Eyre, who puts his wonderfully severe, puritan face to exquisite use, Flaubert emerges as buttoned-up man, a bit of an emotional and fiscal tightwad, who knew much about art and very little about living. He looks as if he has a faint smell perpetually beneath his nose: not the stink of rotting fish but of life itself.

Worth's Sand, on the other hand, although 17 years Flaubert's senior, is the younger by far. Her letters mix the fine art of flirting with grandmotherly wisdom. In Worth's performance you can see the girl burning feverishly in the elderly woman. She has eyes like a cat, and even in death she looks as if she's just nabbed the last of the cream.

Of course, how much this is your cup of absinthe will depend entirely on your taste for this kind of genteel, literary experience - probably best described as Saga theatre - and the extent of your interest in Sand and Flaubert. And of course, wonderful though she is, part of what we're clapping is not just Worth's performance but her achievement, aged 83, in being there at all.