SCARPIA / Left to the imagination: How should an opera be dressed? Extravagantly, to the point of distraction, or stripped down to the bare essentials?

When Stravinsky conceived his entertainment A Soldier's Tale it was not the first time that economic factors forced a significant artistic development. The First World War's austerities drew from the composer a dramatic work tailored for budget staging, and so music theatre, as we now know it, was launched.

The advent of a dramatic musical genre in which the trappings of the stage are reduced to the barest minimum led us to question the whole concept of luxuriant staging in opera and even grand opera. Certainly Wagner lost nothing by being staged at Bayreuth with the barest essentials, and even gained from the removal of visual distractions, the listener being compelled to focus on the inner life of the drama as presented purely through the music.

How much staging does opera really need? Our age's obsession with the past has led to an interest in opera that cannot possibly be satisfied in the theatre alone, where economics dictate that only a tiny proportion of the available repertory can be staged. And so concert performances of opera grow in numbers - an almost inevitable outcome of prevailing cultural and economic forces. But what is lost and gained? A plethora of recent performances in various states of dress has focused the problem anew.

The Aldeburgh Festival revived Britten's television opera Owen Wingrave in concert guise a few weeks ago and certainly threw new light on the work. The opera seemed at its premiere to suffer from television's notorious propensity for converting all allied art forms to its own ends. The visual becomes paramount and the music merely serves.

Freed from the original medium, the music spoke with greater immediacy, and the texture of Britten's orchestra, which carries such power both in delineating character and atmosphere and in pacing the dramatic flow, was focused splendidly from centre stage. The opening section (in which in the original the cameras showed us portraits of successive generations of the Wingrave family) needed imaginative audience participation in the concert hall, as did more complex processes elsewhere; that in itself encouraged an intensity of musical response which is sometimes missing in the opera house.

A few days later, another of Britten's stage works was given a concert performance as part of the Spitalfields Festival in London. The chamber opera The Rape of Lucretia is a work if anything even better able to make its point away from the theatre, owing to its reliance on music's power to narrate action - a factor utilised with uncanny skill by Britten - and also to its static lyric structure.

The famous horse ride, for instance, intercut with a domestic scene at Lucretia's house, speaks directly to the inner eye, and made its point sharply under Richard Hickox's direction; as did the increasing textural intricacy at the opera's dramatic climax, which spoke to us the more intensely without visual distractions. A splendid cast led by Jean Rigby's Lucretia and Donald Maxwell's Tarquinius, plus Catherine Pierard's and Nigel Robson's Male and Female Chorus, sang with drama and passion.

The day before at the Queen Elizabeth Hall, London, we heard a marvellous performance under John Eliot Gardiner of Mozart's Le Nozze di Figaro, in what was announced as a concert performance but was in fact a piece of semi-staged music theatre. Here was proof, if it was ever needed, that economy staging is all that is required for the work to make its maximum impact. Despite a forest of microphones being used for a live recording, the excellent orchestral playing of the English Baroque Soloists and an outstanding cast enabled the audience to use its imagination to maximum effect and see to the heart of Mozart's vision.

Bryn Terfel's magnificent Figaro, Alison Hagley's ideal Susanna, Rodney Gilfry's and Hillevi Martinpelto's outstanding Count and Countess, and Pamela Helen Stephen's heart-warming Cherubino envisaged and projected the drama at high voltage.

What a contrast with the revival of Covent Garden's Don Giovanni, where the trappings of production could do nothing for a performance that failed on nearly every level. Designs that veered between suggestions of a prison compound and a department store display room only distracted; production moves were frequently stilted, while most of the cast seemed vocally out of sorts.

Thomas Allen was a light voiced Don, Karita Mattila afforded only fitful glimpses of her true worth as Anna, Ann Murray, though dramatically intense, was stretched by the tessitura of Elvira, while Hans- Peter Blochwitz was a rather callow Ottavio. Astonishing that with Bernard Haitink at the helm the music drama so lacked immediacy. Only during the closing stages did it splutter into life. Elsewhere everything seemed to be happening a long way off, and we longed for the music to be allowed to make its point.