Tannh&#228;user, Royal Opera House, London<br/>The Bach Pilgrimage, Cadogan Hall, London

A difficult opera is sumptuously sung and lavishly staged, but why were there so many chairs?

Seldom staged in this country, Tannhäuser is Wagner's problem child, a canker of frustrated ambition even in the composer's last days, spent battling angina and flatulence with valerian drops and daily massages in his Venetian palazzo.

For part-time Wagnerians, used to hearing the torchlit grandeur of the Overture and Venusberg Music in concert, the prolixity and piety of the full opera may come as an unpleasant surprise. In Tannhäuser, we have a singing competition without the (qualified) happy ending of Die Meistersinger, Dresden Amens of limited redemptive power, and a compulsive hero without the self-mortifying heroism of Tristan, the Dutchman or Amfortas.

Blessed with a voice to charm the ears of goddesses and scandalise the repressed citizens of mediaeval Wartburg, Tannhäuser is torn, voluptuously and lengthily, as Wagner himself repeatedly was, between an ascetic ideal of virginal womanhood and the allure of a sexual virtuoso. For committed listeners, this is the opera you study to enhance understanding of Wagner's other operas. But can it work as a piece of theatre? Semyon Bychkov, conductor of the first Royal Opera House production since 1987, clearly believes it can.

Spacious in tempi and cinematic in detail, Bychkov's Tannhäuser is an inexorable river of sound, sometimes sparkling with sunlight and oxygen, sometimes still, sucking the listener down to the lightless, airless silt of shame and despair. The same elemental force can be heard in Johan Botha's heldentenor, though it is debatable whether Tim Albery's staging and Michael Levine's set designs would feature so many chairs were it not for the physical bulk of their leading man.

Gilt chairs litter Albery's Tann-häuser, first hurled across a scale model of the Covent Garden proscenium arch in Jasmin Vardimon's choreography of the orgy, then dotted about the shattered theatre that stands for the Hall of Song. Movement, rather than sex, distinguishes Venusberg from Wartburg, a bounding, leaping physicality. This mitigates Botha's limitations. Weary of Michaela Schüster's serpentine Venus and the gymnastic ecstasies of her followers, he sits for much of Act I, only kneeling when another chair can be used for support.

A passing reference to civil war is the trigger for a setting more suggestive of Chechnya than Thuringia. Acts II and III reveal progressive disintegration, the theatre now populated by grizzled, gun-toting partisans and meek women in headscarves. Clichéd as the costumes and movements are (Eva-Maria Westbroek shakes loose her hair to signal Elizabeth's love for the rebel singer), not to mention the candles, Albery respects the pace of Wagner's score, aided by the slow glow of David Finn's lighting. The Pilgrims' Chorus, sung by a choir of 100 and crowned by the Shepherd Boy's (Alexander Lee) innocent contemplation of the green sapling that stands for divine mercy, is stunning.

"Men are fools when it comes to sex," observed a male friend at the second interval. Indeed. It is difficult to sympathise with Wagner's vacillating hero, or the women who love him in their different ways, or the joyless Minnesänger who condemn his paean to physical love, though zealous Walther is attractively sung by Timothy Robinson. Even the Pope has feet of clay in Tannhäuser. Transcendent in self-sacrifice, Westbroek delivers a radiant Act II aria and shimmering Prayer. But you want to shake her for choosing Tannhäuser over Christian Gerhaher's Wolfram. His perilously slow "Blick, ich umher" is heavy with concealed devotion, each consonant a quickening in Wartburg's moribund soundworld, while Hymn to the Evening Star is a miracle of word- and colour-sensitivity. For this alone, a few hours of psycho-sexual bunkum, theatrical compromise and chair abuse is a fair exchange.

Ten years ago, John Eliot Gardiner completed The Bach Pilgrimage, a project of Wagnerian chutzpah that took The Monteverdi Choir and the English Baroque Soloists across Europe and to New York, performing all 198 surviving Church Cantatas. Four of them were featured in last Sunday's anniversary concert, which was hosted by Catherine Bott and recorded for Radio 3. On-stage interviews are a pet hate of mine, and here, the time devoted to talk was approximately equal to the time devoted to performance. The orchestral playing was, of course, divine, most particularly in Kati Debretzni's muted violin obbligato in Schwingt freudig euch empor (BWV 36) and the furious clatter of growling strings and warning brass in Peter Harvey's Day of Judgement recitative in Wachet! betet! betet! wachet! (BWV 70). The Monteverdi Choir sang with customary precision. Rarely, however, was there any spontaneity or uninhibited expressivity.

'Tannhäuser' (020-7304 4000) to 2 Jan. Bach broadcast: 21 Dec, Radio 3

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