The judgement of Paris, France

Surtitles at the English National Opera? Perfidia! Aiuto! Aiuto! ("Treachery! Help! Help!"). You may recall that, about 18 months back, ENO found itself at the centre of a brief brouhaha. It was reported - incorrectly, as it turned out - that the company, which always sings in English, was planning to introduce self-invalidating captions at performances. It's therefore a nicely droll touch that Michael Frayn, in his new adaptation for ENO of Offenbach's La Belle Helene, not only calls for surtitles to be flashed up during the inset parody-operas that are a feature of his version, but also arranges for another, more mischievous innovation. At one point in the piece, the surtitles develop a mind of their own and actually enter into deadpan cross-communication with the characters.

Making intelligent sport with conventions is not unfamiliar territory for Frayn who, in Noises Off, composed a farce about farce and, in Look Look, confronted theatre audiences with an on-stage theatre audience - which meant that you were watching a play about people watching a play. But while he is being justly lauded for his translations of Chekhov, he is new to the game of adapting operas.

Novice's nerves can't have been calmed, in this instance, by the discovery that his friend and fellow learned wit, John Wells, had been commissioned to adapt the very same operetta for Scottish Opera. To the relief, doubtless, of all concerned, the authors could scarcely have taken more dissimilar approaches to the material.

Like the earlier Orphee aux Enfers (Orpheus in the Underworld), La Belle Helene (1864) is a spirited spoof of Greek mythology, turning the story of Paris's abduction of Helen into a teasing satiric commentary on the libidinous mores and glittering corruption of Second Empire France. Offenbach and his librettists, Meilhac and Halevy, trade in the barbed, flippant humour of incongruity and po-faced mock seriousness. The kings of Greece denounce Paris as "un vil seducteur" to a waltz tempo that is itself unsuitably seductive; the stirring patriotic chorus is a resplendent take- off of that in William Tell; the potty-sounding phrase "L'homme a la pomme" becomes the absurd nucleus of a big cod-ensemble.

The operetta's titillating shock value to contemporary audiences and critics can be seen from the first chapter of Zola's Nana (1880), where La Belle Helene is fictionalised as La Blonde Venus and where "this dragging of Olympus in the mud, this mockery of a whole religion, a whole world of poetry" causes "a fever of irreverence" to grip "the literary first- nighters."

Obviously, these days, the figures of classical mythology aren't quite the objects of veneration they once were. Can a late 20th-century adaptation of Offenbach's operetta still give you, as John Wells puts it, the sense "of seeing, at one remove, French Society mocking itself in terms of an Asterix-like classical world" and make that funny and interesting? It's a question on which he and Frayn agree to differ sharply.

An experienced translator (of Beaumarchais, The Magic Flute) as well as author ("Dear Bill" Letters etc), actor (Travels with My Aunt, Anyone for Dennis?) and the Independent on Sunday's restaurant critic, Wells first got to know and love the writing of Meilhac and Halevy when he adapted Offenbach's La Vie Parisienne, a piece "tremendously dense with double entendre". Having to find ingenious English equivalents for the Gallic smut - the courtesan Metella (ie "put it there") was nudgingly re-baptised "Popitine" - was one of the activities that convinced him the original jokes were well worth restoring and that operetta translators have a duty to consider what made the first audiences laugh.

In complete contrast, Frayn, while paying tribute to the witty, crisp lyrics of the original, finds the dialogue scenes "leaden", lacking in conflict (because Paris and Helen are divinely destined for one another), and full of moth-eaten allusions to contemporary affairs (such as the satire on the party games that Merimee organised at Napoleon III's court).

Hence Frayn's decision to re-invent the piece as La Belle Vivette, a backstage drama, an operetta about the creation of an operetta, set not in ancient Sparta but in Second Empire Paris at the Theatre des Gaites.

Helen of Troy is replaced by Vivette, a beautiful singing star. Her Menelaus is a financier; her Paris is a dishy young composer who has written an opera for her on the subject of... Helen and Paris. The fate of Frayn's characters is controlled not by Greek gods but, as is fitting in an age characterised by reckless speculation and gambling, by the investors. A "vaudeville atmosphere" will be created, says Frayn, by a chorus who form a boisterously interactive onstage audience, off-setting that "respectful smiling benevolence, polite applause for the conductor, and everything" that modern punters seem to think appropriate behaviour at a comic opera.

You could argue that the two adaptations reflect their adapters. There's a scholarly love of good, honest indecency in the Wells version; the Frayn displays its author's liking for intricate, wittily self-conscious constructs.

"I suppose," says Wells, whose Scottish Opera version opened in Glasgow last month, "that I was slightly put on my mettle knowing that Michael's version was coming up." It made him, he reveals, want to do "the best possible restoration job on what I think is a wonderful piece of work."

As well as giving hormone replacement therapy to 130-year-old jokes about, say, Achilles' surgical boot, Wells's version slips in some neat gags of his own. Helen is the daughter of Leda and Jove, who raped her in the form of a swan. Her mother's non-resistance serves Helen as a comic excuse for her own amorous laxity. But the original French does not contain the pun that winks out from Wells's text: "Take the example of my mother / When my papa came swanning by". And Paris's saucy comment that the goddesses on Mount Ida "move in most mysterious ways" reinforces, with its cheeky reference to Christianity, the parallel that is also drawn in the production's scenic allusions, between pagan Greece and the Catholic church of the Second Empire.

Relocating the piece in the period of its first performance, Frayn makes the background the foreground; the parallels he wants to suggest are those between the Second Empire and Britain in the 1980s.

Both authors are agreed that the "absolute nightmare" to adapt was the number entitled "Ces Rois Remplis de Vaillance". It's the ditty in which the Greek kings come forward and introduce themselves in lines whose trickiness is a matter both of the rhythm (dum dum dumdiddydumdum dumdiddydumdum dumdiddydumdum) and of the fact that there's a nonsensical lopping of syllables in the second line of each verse, as for example in Menelaus's "Je suis l'epoux de la reine / -poux de la reine, -poux de la reine / Le Roi Menelas".

Wells characteristically remains faithful to the form of the joke, while also improving on it. Instead of mere nonsense, his loppings produce subversive double-meanings of which the bombastic monarchs are sublimely unconscious, as in "And fools dismiss Agamemnon / Miss Agamemnon, Miss Agamemnon" or "His strength renewed Agamemnon / Nude Agamemnon, Nude Agamemnon".

As you can see from the extracts printed below, Frayn side-steps the original gag but seizes marvellously on the "no, after you; no, after you" feel of the music. He has also had the inspired, if recherche, idea of turning First and Second Ajax, the Siamese-twin dimwits of the original, into that creepy, inseparable real-life writing duo, the Goncourt Brothers, whose Journal was, they claimed, the "effusion of a single ego". Here, as they leap-froggingly collaborate on the simplest statements, their union gets its comic comeuppance.

Of course, all this worry and effort over wording involves a touching faith in the intelligibility of opera libretti even when English'd. Wells declares himself " very well served" by the "brilliant diction" in the Scottish Opera staging. With La Belle Vivette due to open on 11 December, the diction of the ENO cast awaits assessment.

Michael Frayn once wrote an amusing column (reprinted in his new collection, Speak After the Beep) about the humiliation of getting utterly defeated by the baffling plot at an ENO production of Mussorgsky's Khovanshchina. Because he speaks Russian, friends kept appealing to him for help (somewhat illogically, given that it was being sung in English) and, as he records, "my reputation and authority declined from interval to interval". In the intervals of La Belle Vivette, he will be able to pose, with no small justification, as the leading expert on its narrative structure.

n 'La Belle Vivette': in repertory at ENO from 11 Dec to 24 Jan. Booking: 0171- 632 8300