He's flanked by two other performers - the veteran British actor Julian Glover, and the Iraqi actor Falah al Flayeh - whose lines interlace English and Arabic. Andrew Steggall, the nervy young Brit who is directing, breaks off every few minutes to check that his music director, Robin O'Neill, and the Iraqi composer, Ahmed Mukhtar, are both happy: Mukhtar is not very. They've hit a sticking-point: they can't agree on whether to segue into an Iraqi marching song via "Rule Britannia" or "The Star-Spangled Banner".
Meanwhile, two other Iraqi actors await their cues; the English translator Rebecca Lenkiewicz and the Iraqi translator Abdulkareem Kasid brood on script-changes; the Iraqi film-maker Hayder Daffar - whose terrifying documentary on post-war Iraq, The Dreams of Sparrows, is now being acclaimed in the West - is busy with his camera.
Inspired by Russian folk tales and written in the shadow of the First World War, Stravinsky's Soldier's Tale is now being used to reflect the ongoing conflict in Iraq, and the Faustian pact that its hero-victim makes with the devil is being adjusted accordingly. So the devil's book of the original, a primer on how to make money, is now playing a variety of roles, functioning as the Koran, the Bible, the "dodgy dossier", and even a map of Iraq's oilfields.
"It's about selling ideology," explains Steggall. "And if you follow its advice, it will take you to Hell." But he insists that the piece is not a polemic about Iraq: "It's a story about choices, and it's applicable anywhere."
But it does, of course, readily apply to Iraq, most obviously in terms of the loss, which is its leitmotiv. If the Soldier is constantly losing things - his violin, his family, and even his manhood when he's cuckolded by his fiancée - the Iraqi performers, all of whom have lost friends and relatives, have a crueller acquaintance with this theme. They know what it means to be a soldier. Mukhtar, who spent years evading Saddam's police after absconding from the army, takes the show very personally: "This piece is my story. The Soldier is the Iraqi people now, and, like everybody else in the cast, I have first-hand experience to draw on."
And if this show - a co-production between The Motion Group and the National Theatre of Iraq - is a one-off, so was its genesis. Just over a year ago, Steggall and O'Neill put on a single performance of The Soldier's Tale at the Old Vic: Jeremy Irons was the central character, and they used the event to launch what they then simply called their "Iraq project". Then - flying in the face of common sense, plus official discouragement from the Foreign Office - Steggall took himself off to Baghdad to trawl for actors. Steggall took O'Neill on a further trip to Baghdad, but they were ordered out by the British embassy. They held their auditions in Saddam's infamous Red House in the Kurdish city of Sulaymaniyah.
And that is what they're transforming the Old Vic into now. "We've emptied the stage, cleared out everything so it's just bare walls, which we are dressing and painting in the style of the Red House," says Steggall. "And on the floor will be just an expanse of sand - a wasteland, Middle Eastern in flavour. Our narrators will sit either side, Julian in an English pub, Falah in an Iraqi café, each telling their story. And gradually it will become clear how their respective soldiers have become foreign, alien to each other, though the audience will finally realise they are one and the same.
"We will show how the wrong Faustian motives result in the protagonists becoming enemies, remote and alien to each other. When they defeat the devil they win back their soul. When we tour the show to Iraq, we hope the audience will realise that we have a common language." Tour to Iraq? "In a very slimmed-down form, with an all-Iraqi cast. It will be unannounced - there'd be no point putting that in a paper."
When I catch Mukhtar at a stressful point in the collaboration, other tensions are revealed. "I told them to be careful, that we are artists, not politicians, and we want to present the truth," he says. "Embarrassing Tony Blair should not be the aim - even though I don't defend him. The Iraqi people's sufferings under Saddam are more important." He's unhappy at the imbalance between the two parts of the ensemble, with just three Iraqi players facing seven European instrumentalists. He knows the problem is finance, but "Arabic clarinet-playing is completely different from the European style". On the other hand, Mukhtar feels comfortable with Stravinsky: "There's something very Eastern about his music, which I feel close to."
Iraq is elbowing its way into this cosy corner of London in a variety of ways. Mukhtar talks sadly of the music centre he's been trying to set up in Baghdad, and Abdulkareem recalls his own flight from Saddam's inquisitors, being stuffed into a tanker alongside other refugees: "I asked the man jammed on top of me if he was OK, and he said: 'I feel as fresh as a rose - and you are my vase!' Iraqi poetry exists even in such desperate situations."
On the other hand, since the Iraqi actors are all sit-com stars back home, they're getting free meals in London restaurants owned by their fans, and they're revelling in the chance to work in a climate free from fear. "We want to show that soldiers everywhere are powerless to make decisions about their lives," says Hayder. "Our job is to spread a message of peace. Our conflict in this play is a conflict of love."
'The Soldier's Tale', Old Vic, London SE1 (0870 060 6628), Thursday to 4 FebruaryReuse content