As the curtain rose on Sweeney Todd, the lady in front of me was tutting her disapproval. The stage was almost all taken up with the ENO Orchestra, a demure row of black staves in front awaiting the soloists. “The scenery’s her favourite bit, usually,” her friend explained. “She’s so disappointed.” Well, she didn’t remain disappointed for long. Bryn Terfel, Emma Thompson and the cast filed in calmly, smiling and carrying scores, and began singing the first “Ballad of Sweeney Todd” quite politely; but then, with a challenging glare at Emma Thompson, Bryn Terfel threw his score to the floor. Not to be outdone, Thompson, after a comic pause, followed suit; and suddenly, pandemonium struck. The ensemble (some of whom had been disguised as audience members in stage boxes) overwhelmed the stage in the theatrical equivalent of trashing a hotel room, tearing, ripping and upending whatever they could find (including a grand piano). Banners rolled down to proclaim the setting; curtains opened to reveal a huge backdrop of modern graffiti, with Guy Fawkes masks clearly locating us in the economically dissatisfied, socially uneven London of today. The orchestra, undeterred, played on. The suspense and tension on stage was suddenly electrifying: Sweeney Todd had begun.

There is no doubt that the ENO are making a grand gesture with this Sweeney Todd. It is to herald a new return to musical theatre as a key aspect of their repertoire; it is, significantly, a transatlantic production which points to a strong artistic friendship with Broadway; and they have certainly gone all out on the luxury casting. Bryn Terfel draws the opera faithful, while Emma Thompson endows the stage with Hollywood glamour. And whether you count yourself in Team Terfel, Team Thompson or both, the two leads give fabulous performances which linger in the memory. Lonny Price's production is also tense and grisly enough to make it wise to eat beforehand. 

Terfel is brooding, bitter and poignant as Todd, giving his character a very real sense of nastiness born of absolute misanthropy. His singing is rich, deep and delicious as always, though he has to rein back his voice at all times to avoid exploding his microphone: yes, they all have them in this production, I'm afraid. Despite these constraints, Terfel's perfect placing of every word of his part, spoken or sung, is a particular delight. 

Emma Thompson's superb acting, refreshingly down-to-earth Cockney accent and naturally skilful comic timing make for a truly hilarious Mrs Lovett, utterly chilling in her calmly practical attitude to corpses. If you have only seen her on screen in the past, Thompson's immaculately snappy, viscerally physical approach to her role is a revelation. Her singing voice is appealing and expressive, always shaped by her characterisation: not shy of shrieking or sobbing when occasion demands, Thompson remains musical unless there is a convincing dramatic reason to do otherwise, in which case, she takes risks - and reaps rewards. Their duets together feel progressively more tragic, as Mrs Lovett allows herself to be drawn ever closer to the demon barber, while he turns inexorably inward, losing all interest in life as he immerses himself in slaughter.  

We have another treat on stage in the form of a very slick Ensemble, who constantly impress with their varied palette of warm voices, injecting energy constantly with sharply-executed choreography. The whole company interact with the ENO Orchestra throughout the piece, constantly adding little touches of humour; even our conductor, David Charles Abell, is drawn into the production. Putting the orchestra on stage challenges both players and singers, but it's an experiment which gloriously justifies itself here, deepening the drama by creating a sense of order (the orchestra) at the mercy of rebellious chaos (the production going on around it, stealing from and attacking it). 

The smaller roles are more of a mixed bag, or, if you will, an uneven pie filling. The danger for all such small characters is that, beside the developed psychological portraits of Todd and Lovett, they can (and often do) seem mere caricatures. John Owen-Jones is an outstanding Pirelli, the showman barber who becomes Todd's first victim, wheedling and menacing by turns. Philip Quast's Judge Turpin is ponderous, but remains truly disturbing in his self-flagellation scene as he fantasises about his ward Johanna. Rosalie Craig is affecting as the Beggar Woman, whose appearances are repetitive and annoying through no fault of hers. Alex Gaumond is a nicely creeping, sweaty-palmed Beadle Bamford. Jack North had some fine scenes as Tobias Ragg, particularly towards the gruesome finale; but, even with a microphone, some of North's words were lost in shaky and uneven moments, detracting overall from what could otherwise have been a very moving performance. Katie Hall gives Johanna the straightforward Disney Princess treatment, a sensible move, but her character remains profoundly unmoving. Matthew Seadon-Young doesn't get far as the romantic hero Anthony Hope: the intention seems to be to contrast his youthful innocence with Todd's barbarism, but beside such a fabulous Todd as Terfel, young Anthony pales into insignificance.  

Sondheim's music has a restless energy to it which draws you in. Even the darker harmonies are still beautiful: throughout, there's a mixture of prettiness and bite which often makes for a satisfying listen, though the love scenes flag noticeably. Still, the general effect is sharp, refreshing and certainly great fun: the question remains, is it opera? The ENO's acceptance of West End conventions like microphones, a certain chattiness in the programme, and what felt like an automatic standing ovation to close, seems to indicate they think it isn't. Their appetite for a new audience has inspired them to diversify, which is entirely healthy, and heralds an exciting new chapter for the Coliseum. Let's just hope it doesn't tempt them to sin against their existing audience too often, either.