At its centre is Robert, primus inter pares in a tight ensemble of 14 characters (Company has no chorus) and an independent man in 1960s/70s Manhattan observing the relationships of his married friends with a mixture of fascination and resistance. He is 35, attractive, personable, and the pressure to settle down with a nice girl has reached crisis point. So, through the songs, he takes stock of why he is alone - by accident or choice? - and whether a relationship would make him happier.
The answer, of course, is that there is no answer. It's an equivocal piece with an ending that Sondheim periodically changes; you could say the same of the songs, which are fascinating to hear at long last in their original context. To my knowledge, Company hasn't had a professional staging in London since 1972, so the book isn't well known. But the songs - "Sorry/ Grateful", "Being Alive", "The Ladies who Lunch", "Barcelona" - have had an independent life, stopping enough Sondheim gala nights over the years to qualify as the secular hymnody of late 20th-century soul-searching. And more often than not we've been encouraged to hear them as affirmative statements, especially "Being Alive" which has become the feelgood anthem of Aids benefits the world over. But onstage, "Being Alive" isn't affirmative at all. It's riddled with anxiety, self-doubt, unrealised longing - and beautifully done at the Donmar by Adrian Lester who doesn't have a richly textured voice but uses what he has with an engaging artistry. All cutely passive charm and easy, off-the-wall intelligence, he must be the most sympathetic man in British music-theatre. It's an achievement to leave the show without falling in love with him - if only a little (to steal a Sondheimesque qualification).
I must leave it to Robert Hanks (see page 13) to consider the drama of Sam Mendes's production; but as a musical experience it's stunning, with an energy and power that obscures the fact that (if you sit down and analyse it) the ratio of speech to song heavily favours the former. And part of the energy derives from the fact that the sound of Company has been discreetly updated. This show, inevitably, is a period piece, fixed in the 1960s/ 1970s. Its preoccupation with Manhattan marriageability feels like an encounter between Jane Austen and Neil Simon, and it's original scoring was replete with the spangled electronic sounds of 1960s urban music. But for 1995 the dialogue has been toned up (with a clear suggestion that Robert might be gay) and the music toned down. The cheesy, synthesised glissandi, for example, that punctuate the lines of "Sorry/Grateful" have been reallocated to an unsynthesised, almost pastorally post-modern oboe. And if such things sound de minimis in print, in actuality they make a difference: subtly but materially. Practising Sondheimites won't be disappointed - the piece is all there and more, with "Marry Me a Little", a song dropped from the canon long ago, reinstated - but neither will newcomers expecting a fresh show that speaks for today as much as for a quarter-century past. Company is one of the most intriguing, exhilarating and unsettling landmarks of modern lyric theatre; and what you hear and see at the Donmar serves it superbly well.
On the subject of newcomers to Sondheim, it's time the myth was laid was to rest that he's an unapproachably abstruse composer for the genre in which he works. If that were true his work wouldn't be done by amateurs; but it is, and I saw recently an amazingly effective Sweeney Todd done by the NatWest Theatre Company in London. The conductor, Jonathan Wix, was a young music graduate but the cast was entirely amateur - bank clerks I suppose - and everybody coped with the rhythmic and melodic intricacies of the score in a way that shouted from the rooftops their commitment. Unapproachable, untuneful Sondheim? Hardly.
If Company is a model of how to deal delicately with a period piece, La Belle Vivette at ENO is not. La Belle Vivette is in fact Offenbach's La Belle Helene, rewritten by Michael Frayn on the grounds that the piece is no longer viable in its original form. But this will come as news to many Offenbach enthusiasts, with whom I'd agree that all Helene needs is a nip and tuck and a decent translation. Given that small help, it's an extremely funny piece. Michael Frayn's rewrite is not.
What he effectively does is distance the comedy to arm's length. A spoof on ancient Greek mythology becomes a spoof about a spoof, an operetta about putting on La Belle Helene in Offenbach's own Second Empire France. And if you read the new libretto, which ENO supplies with the printed programme, you'll find some sharp rhymes. Worthy, almost, of Sondheim. But their effectiveness is small-scale. Across the expanse of what, in director Ian Judge's hands, becomes a big, complex show, they barely register; and the situational peg on which they hang just isn't strong enough. Essentially it's a life-into-theatre conceit that might work in a West End farce but doesn't square up to the added factor of music.
All this leaves Ian Judge and his cast with an impossible task. There are some good visual gags, fine individual performances from Neill Archer and the riotously entertaining Andrew Shore, and Lesley Garrett sings prettily in the title role (pity she has to speak as well), but it comes ultimately to nothing. Moral of the tale: if it ain't broke ...
Finally, the Royal Opera's Aida turns out to be better in revival than first time around. The restrained good taste of Elijah Moshinsky's production feels more engaging than before; Daniele Gatti's clean, fast- tempered conducting more urgent; and the cast, including an impressively deep-thoated Amneris from Nina Terentieva, an impactful Amonasro from Simon Estes, and a ringing Radames from Michael Sylvester, is certainly an improvement. Above all there's a magnificently virile Aida from Sharon Sweet whose tank- like imperiousness is a bit grand for an Ethiopian slave-girl (albeit one of secret royal birth), but no matter. The voice is full and true throughout its range, and positively glorious at altitude. With so much, attitude can be forgiven.
'Company': Donmar, WC2 (0171 369 1732), all week. 'Vivette': ENO, WC1 (0171 632 8300), Mon, Wed, Thurs. 'Aida': ROH, WC2 (0171 304 4000), Tues & Fri.