Inside Monteverdi, South Bank Centre, London

The full Monteverdi

In February 1607, an excited Mantuan courtier wrote to his brother in Rome: "Tomorrow evening His Highness the Prince is to have performed... a piece that will be unique because all the performers speak musically."

Actually, experiments in sung drama had already been going on in Florence and Rome for more than a decade. If Monteverdi's L'Orfeo still speaks to us as the first true opera, it is for the heightened flexibility of its vocal writing, the tight cross-patterning of its musical forms and the way they seem to interact to create a genuine dramatic tension over five acts running for 100 minutes.

Yet it is possible that, to some extent, we read those qualities back into the work from the subsequent development of opera, and that Monteverdi and his librettist, Striggio, had other priorities, in writing it, of a more ceremonial, emblematic, even philosophical kind. Philip Pickett, for one, has long laid stress on Monteverdi's involvement in neo-Platonism and the importance of considering the original performance conditions in approaching his first opera.

However, in a characteristically voluble preview talk to his new Queen Elizabeth Hall staging for the South Bank's Inside Monteverdi weekend, Dr Jonathan Miller proceeded to rubbish the whole idea of authenticity. Truly great works have "deep structures" that transcend their original conditions, he argued, and the task is to reinterpret such structures meaningfully in the here and now.

In the event, the two approaches tended to cancel each other out. While Pickett disposed his orchestra of strings, lutes, cornets, sackbuts and so on as per period on either side of the stage, and beat his way, at times a trifle prosaically, through Clifford Bartlett's scholarly edition, Dr Miller put his cast through a series of tableaux vivants - slow-motion gestures and dance patterns that some of the singers plainly lacked the appearance and training to bring off convincingly.

There were moments of tentative ensemble between voice and continuo, moments of "ghastly good taste" in the staging, even, when one might almost have been back at an earnest university production in the late 1950s. What saved the evening were some sterling individual performances: Joanne Lunn plangent as La Musica; Julia Gooding mesmeric as the Messenger of Euridice's death; Michael George darkly stentorian as Plutone; and, of course, that master of Baroque florid song Mark Tucker transfixing in the passionate, fine-spun pathos of the title role.

Disembarrassed of Dr Miller's mystic passes, Tucker was back in more ebullient form the following afternoon for an absolutely fizzing bill of Monteverdi duets from the Seventh Book of Madrigals (1619) and scenes from the later operas with his equally exuberant fellow tenor Lynton Atkinson, accompanied by the sparkling harpsichord of David Roblou - who threw in the odd Merulo or Gabrieli solo by way of complement. The sound of the two equal voices, sensuously interweaving or passionately competing over the keyboard's spicy tingling, haunted the ear even after Andrew Carwood and the voices and instruments of The Cardinall's Musick had brought the weekend to an inspiriting conclusion in a programme exploring the church music other than the great Vespers of 1610.

It ranged from the luminous contrapuntal interweavings of the Sanctus from the Missa In Illo Tempore (1610), by way of the precipitate virtuoso bass setting "Ab aeterno ordinata sum", impressively sung by Robert Macdonald, to the Magnificat that crowns Monteverdi's late volume Selva Morale e Spirituale (1640) - exemplifying his ability to grip many sections together through a kind of proportional grid of rhythmic relationships.

The enthusiastic response to the Magnificat, as to the whole weekend, raised the possibility of further South Bank festivals devoted to major early-music composers. Next year, how about a concentrated weekend of the many-sided William Byrd?