There was a time when the operettas of Gilbert and Sullivan were part of the education of every second middle-class Irish child. I never appeared in one myself - having neither the singing nor the acting ability - but how many Mikados and Gondoliers have I seen, how many Pirates of Penzance, Yeomen of the Guard and how often have I sat through H.M.S. Pinafore, Patience and, even, less frequently performed works like Iolanthe and Ruddigore. To this day, like most of my contemporaries, I still know the words - approximately anyway - of dozens of the songs: "The flowers that bloom in the spring tra-la . . . ", "Take a pair of sparkling eyes . . . ", "When I was a lad I served a term/ As office boy to an attorney's firm . . . " "It is, it is a glorious thing/ To be a Pirate King . . . " and so on and on.

I had an aunt who played in an amateur orchestra, which accompanied many of these productions, and I followed her around from school to school, quite happily I must say, so the tunes became burned into my brain.

Who were the writers of these works, progenitors of the modern musical and still greatly loved? They came from totally dissimilar backgrounds and were of totally dissimilar temperaments. Gilbert, a tall irascible man given to quarrels and with a wickedly barbed wit, was the grandson of a tea merchant and son of a naval surgeon who had retired to live on a considerable family inheritance. His parents' marriage was unsuccessful, and they finally separated. As a young man, he showed little sign of promise. After university in London, he worked for a few years as a minor civil servant, until freed by another inheritance. Thereafter he became an aspiring barrister, but most of his energies seem to have been devoted to writing pieces for a comic magazine, Fun, theatrical burlesques and then plays.

Sullivan, from a less well-off but happier family, was by contrast easy-going, charming and obviously highly talented. His grandfather, a squireen from Co Cork, had fought in the Napoleonic wars and ended up as one of the guards of the defeated Emperor on St Helena. His father, a musical jack-of-all-trades, was eventually appointed bandmaster at the Royal Military College in Sandhurst, and this marked the first upturn in the fortunes of young Arthur, his second son. He became a chorister at the Chapel Royal at St James's Palace, where he first came to the attention of royalty, a useful connection he was to keep all his life.

He won scholarships from there to the Royal Academy of Music in London and to the Leipzig Conservatory, where he became friendly with such giants as Liszt. Now a composer, he was marked early on as the English successor to Mendelssohn, the great figure of Victorian music. It was to prove a mixed blessing, for it meant that his light compositions, for which his real talent lay, were always regarded as artistic slumming, both by members of the musical establishment and himself. But who now remembers his grand opera Ivanhoe or indeed any of his "serious" works, apart from the hymn Onward Christian Soldiers and that lugubrious song The Lost Chord - how much better the Jimmy Durante version is! The two came together and, after a forgotten start entitled Thespis, wrote an enormous hit in the one-act Trial by Jury. For more than 20 years thereafter they were to dominate the English musical stage with new works. But it was never an easy collaboration.

Apart from their very different temperaments, there was Sullivan's constant feeling that what he was doing was beneath his talents and that he was being pushed by his partner into a way of working that demeaned his music. Gilbert was what might today be called a control freak. He wrote, directed and, sometimes, designed the Savoy operas, and also tried to involve himself in the day-to-day business affairs of the company. He was under no illusion that he was producing high art (indeed he himself dismissed The Gondoliers as "ridiculous rubbish" shortly after it opened) but expected things to be done his way and to be properly paid. The partnership finally broke down, ostensibly in a row with D'Oyly Carte over the cost of new carpets for the auditorium of the Savoy Theatre. Sullivan took the manager's side and, though they produced a couple more, unsatisfactory shows, they were never to be friendly again and, when the composer died, had not spoken to each other for years.

There are still many people, I suspect, for whom G&S represent the summit of all dramatic and musical endeavour. But, truth to tell, there is about them nowadays the whiff of cold porridge. Time has caught up with them in a way it has not with greater works. The words are, without question, witty and wonderfully deft, and the is music memorably tuneful, but for lyrics give me the sly irony of Cole Porter, or for music the ravishment of, say, The Magic Flute. Part of it, of course, is not the fault of Gilbert and Sullivan at all. More than any other writers they have suffered from the clammy embrace of the amateur. When the pair were starting their collaboration, in an effort to get away from the stock gestures and style of so many of the professionals of the then London musical stage, they cast partly from amateurs and music students. Though they themselves were supremely professional and supervised their productions in a way which was unknown for authors in their time, it's as if the taint of the part-timer has stuck with them.

The process was aided, too, by the keepers of the flame, the D'Oyly Carte family. Richard D'Oyly Carte kept the often-quarrelling Gilbert and Sullivan together for years, gave them a theatre and made their fortunes. It is undeniable that, without him, there would have been no Gilbert and Sullivan canon. But the determination of his family for three generations to preserve Gilbert's concepts of staging led to a staleness and a dated feeling about most productions.

To go to traditional Gilbert and Sullivan shows nowadays is to enter a rather dusty Victorian institution: safe, predictable and utterly unchallenging. That this is exactly what many amateur musical societies want - together with loads of parts and big choruses - doesn't make it any more exciting for the rest of us.

Up-dated versions of the shows haven't always worked, but there have been some that indicate there may be life in the old dogs yet. Jonathan Miller did a hilarious reworking of The Mikado, in which the cast were clad in English Edwardian costumes rather than Japanese, and a brash, camp version of The Pirates of Penzance on Broadway, later replicated in Dublin and London, had a very welcome freshness and vitality to it, whatever the traditionalists might think.

Maybe Mike Leigh's new film about Gilbert and Sullivan, Topsy-Turvy, will encourage more original productions. Gilbert, as well as being the father of modern song lyric writing, was a theatrical innovator in his day, while Sullivan's tunes remain as easy on the ear as ever. Enter, one hopes, some new, inventive stage directors, and who knows what future there could be for the pair.

Topsy-Turvy opens at selected cinemas on Friday