The title role of Bellini’s Norma requires a true prima donna. She must be a powerful singer who exudes drama and dominates the stage while producing intricate bel canto with occasional coloratura; she must also have close to Wagnerian levels of stamina. For Opera Holland Park last night, Yvonne Howard made a pretty decent fist of the role.

Howard’s voice certainly had the required power and stamina. Helped by a striking flowing green costume, she was an imposing presence on stage and acted convincingly the part of the priestess who is a powerful clan leader externally but a soft (if occasionally homicidal) mother underneath. Howard’s phrasing did full justice to Bellini’s flowing lines, and her timbre was mostly beautiful, albeit with the occasional harsh note. Her voice may lack the flexibility to succeed in intricate decoration, but this was a fine performance.

Howard was well matched by Heather Shipp’s attractive timbre as Adalgisa: their duets were intricately woven and Shipp showed herself more than capable of taking command of the stage at the appropriate moments.

As Norma’s faithless lover Pollione, Joseph Wolverton did not approach the same standard. While he acted well and his timbre and phrasing were fine, some early high notes cracked horribly and he was unable to summon up enough power to make himself heard above the orchestra, let alone to impose his presence vocally. It’s a key role, and this was a performance that disappointed.

Which was a pity, since this was production was excellent in most musical aspects. Under the baton of Peter Robinson, all of the different moods of Bellini’s score came through delightfully and perfectly weighted, ranging from highly dramatic punch to martial vigour to the fluid mysticity of the famous “Casta Diva.” And while I may have criticised Wolverton’s Pollione overall, the last duet between him and Howard achieved a rare intimacy.

Olivia Fuchs and designer Niki Turner’s staging is built on the fact that the whole opera takes place under the shadow of an occupying army (the original is set in the Roman occupation of Gaul, although the only Romans in the libretto are Pollione and his sidekick Flavio). In the overture of this production, the stage is filled with soldiers in desert fatigues, enthusiastically engaged in drinking beer, larking about and raping the local women, with the stage surrounded by a cage topped with barbed wire and security lights. The cage and the soldiers are a constant presence throughout the opera: squaddies tote assault rifles on a watchtower or type things into a computer at a security point which forms the only entrance onto the stage. The whole thing breathes “Abu Gharaib” and  “Iraq occupation”.

Fuchs gets excellent acting performances and the overall concept is perfectly promising, but it comes out half-baked. Fuchs and Turner either didn’t dare or thought it inappropriate to present the Druids as Iraqi civilians, so the army appears to have invaded a sort of oversized hippie colony, with a lot of beads and tassels for the women, and a confusing combination of workers’ overalls and casual Americana for the men (the Gauls are all employed within the invaders' camp). It’s not at all clear who is being caged in, since the Gauls’ sacred forest appears to be inside the cage, and the single-entrance stage layout enforces some decidedly strange behaviour, like the unarmed Druids having to overpower the heavily armed soldiers in order to assemble for Act III, in which they mysteriously decide to use their sacred tree as the pyre for Norma and Pollione.

I was constantly irritated by the surtitling, which inserted some horrible anachronisms, diligently suppressed all use of the words “Romans” and “Rome” and which substituted “Gaia” for “God” or “Irminsul” – since the libretto frequently refers to the Gallic god as being bloodthirsty and violent, the name of the peaceful earth mother seems a particularly daft choice. And presumably, whoever did the surtitles is assuming that none of his audience know the opera, understand enough Italian to pick up the word “Roma” or have simply read the synopsis.

Norma is an opera that’s performed far less often than its reputation and popularity on record would suggest, largely because of the difficulty of casting the title role. This production excels orchestrally, is well acted throughout and has fine vocal performances from its two female leads. All this makes it well worth seeing, in spite of other imperfections.