We are glutted with farces," complained Charles Mathew of Covent Garden. "What we want nowadays is a good five-act comedy of modern life." Playwright Dion Boucicault duly obliged, and produced the first of his many hits, London Assurance.

The play is set in 1841 - the year when the Great Western Railway from London to Bristol opened. Not that Boucicault's character Sir Harcourt Courtly would necessarily have thought railways a good thing - visiting the country from London to claim a new wife, he finds the buzzing of bees and the baa-ing of sheep equal causes for alarm. Sporting a curly wig of suspicious blackness, Sir Harcourt is played by Gerard Murphy as a mixture of panto dame and Mr Toad. His bulging eye is affixed on country squire Hathaway's daughter Grace (Clare Corbett): "Never seen the lady before," he booms. "But I am about to present society with the second Lady Harcourt". Needless to say, giggly Grace is many years his junior.

However Sir Harcourt's eye soon wanders in the direction of one Lady Gay Spanker (Geraldine McNulty, pictured with Clare Corbett). Her ladyship's life centres entirely on the hunting field, and there is no problem that cannot be solved by use of a horsewhip. Her laugh is loud enough to shake the very rafters of the Watermill. In a precursor of music hall sketches yet to come, Lady Spanker has a downtrodden husband (Christopher Ryan), who appears to be exactly half her height. A scene in which, fortified by copious quantities of Burgundy, he suddenly contradicts his wife is a highlight of the evening.

On the opening night, some members of the cast seemed rather ill at ease within the skin of their characters, and with the timing of their lines, either because the production needs time to run in, or because director Nikolai Foster (Mathew's original advice to author Boucicault notwithstanding) hasn't quite decided whether to play London Assurance as a comedy or a farce. Even allowing for the tedious, preachy ending, however, it's still easy to see why this show was a hit of its day.

London Assurance continues at the Watermill, Bagnor, Newbury, until May 17. Tickets: 01635 46044 or online at www.watermill.org.uk The production tours to the Oxford Playhouse, from May 19-24.