On cue with the first piano chord, a frenzied whooping sound bursts from the mouths of 26 young boys. Ranged in orderly twin lines, they're trying to sound like disorderly monkeys. "Right boys," says the conductor, stopping them with a sweeping gesture, "I want monkey sounds that have no pattern about them - just your view of how a monkey would sound, without being one. Some of you will find it easier than others - yes, you, Guy."
He glowers at a dark-haired 10-year-old in the front row, who immediately stops scratching his armpits. Then, with a firm downward beat, the conductor triggers a new and more demented chorus of ooh-ooh-oohing, rising with the chords of the piano. This is Manchester Boys' Choir (MBC) - regarded as one of the finest of its kind in the world - doing warm-up vocal exercises in rehearsal, under its artistic director, Jeffrey Wynn Davies.
It is a wet Monday night in a primary school hall in the suburb of Didsbury. There is no rehearsal time to waste. The choir has a major concert with Chetham's school of music at Manchester's Bridgewater Hall on April 11 and a performance of Mahler's 3rd Symphony with Opera North in Leeds the next day.
Once the post-chimp giggling has died down, Mr Wynn Davies needs just one movement to bring the two dozen trebles in right on time for the next vocal exercise - singing A-E-I-O-U to each note of the scale. "Come on, open your mouth, Alex," he shouts. "You're not training to be a ventriloquist."
The discipline of these sweatshirted boys, most aged nine to 13, is astonishing. Before the evening is out they will have sailed through songs in Finnish and Russian and battled with the complex time signatures and tonal structure of Britten's Missa Brevis, before bursting out of the hall to kick a football around in the school yard.
It is difficult to believe that this local authority-funded choir has reached these artistic heights with an open-door policy; in contrast to most other top choirs, MBC does not hold auditions. It also has an unusually wide social mix. Although 11 of the 26 choristers come from independent schools, 15 are from state schools, nine of them in inner-city areas such as Longside, Clayton, Harpurhey and Hulme. There are children of single parents and others whose parents are unemployed.
To encourage boys from non-traditional backgrounds, Manchester LEA's music service meets all the running costs. Boys have to pay only for the foreign trips, and subsidies are available for those who cannot afford them. The music service insists that no child should be excluded because of lack of money. There is a lot of lift-sharing to make sure all the boys get to every rehearsal.
But perhaps most difficult to believe, looking at the bright faces of the boys being put through their paces, is that only 18 months ago the choir was almost torn apart after its founder and then musical director, Adrian Jessett, was arrested and charged with the rape of a former choir member.
In April 2002, he admitted to eight sample charges of indecent assault dating back to 1996, all relating to the same boy, then aged 13, and was jailed for four years. The rape charge was dropped.
Jessett's arrest and jailing dealt the choir a blow that left all involved - the local authority, parents and choristers - shattered. The question everyone was asking was: could the choir survive this numbing betrayal?
MBC was able to carry on, under a new regime set up by Mr Wynn Davies, an international choir trainer, and his choir director wife, Fiona Clucas, because a groundswell of opinion said it was too special to abandon.
Deborah Catterall, musical director of the National Youth Training Choir, took some rehearsals after Jessett's arrest. She says: "There was a determination to succeed, a kinship and a friendship. Because of that, there was a real discipline. The choir had to go on."
To understand the impact of the events on everyone connected with MBC, it is necessary to know something about Adrian Jessett himself. This was a man whose life and passion was the choirs he had founded.
Jessett, who is in his early fifties, lived with his mother, Edna, who accompanied him to every concert, and the choir on most trips. He had a formidable reputation in the music world as a genius for getting the best musically out of boys, but is also described as a "Jekyll and Hyde" by a former accompanist, for the rapidity with which he could switch from the epitome of charm to ferocious anger.
He set up MBC in 1981, developing a hierarchy consisting of a junior choir and training choir feeding into the elite concert choir plus a choir of teenage boys who wanted to keep singing after their voices had broken. The system continues today.
His control was total. Parents signed a contract agreeing to rehearsals two nights a week, plus regular all-day sessions on Sundays, up to 20 concerts a year and overseas tours in the summer holidays lasting up to three weeks.
Boys were not allowed sheet music; every piece had to be learned by ear. In concerts, choristers would not be told what they were singing until they were about to walk on stage.
Success was almost immediate. With his non-audition concert choir of boys, Jessett won the international youth choirs class at the International Eisteddfod in Llangollen. Trips to Finland, Hong Kong, Russia, Australia and the United States followed, as well as Royal Command performances. MBC was in demand to perform with the BBC Philharmonic and the Halle Orchestra.
When Manchester's Bridgewater Hall opened in 1996, MBC was asked to be choir in residence.
Requests came from all over the world for MBC to supply boy soloists for productions at famous venues such as La Fenice in Venice and for English National Opera.
So when the head of the Manchester music service, Allan Jones, received a phone call from Jessett on September 11, 2001, saying he had been arrested, Mr Jones resolved to ensure that the choir would survive. "I was in shock," says Mr Jones, who had known Jessett since before the choir's establishment and had accompanied the boys on several trips. "I have travelled extensively with Adrian Jessett and nothing I ever saw gave me any inkling or thought of a sexual crime," he says.
Having suspended Jessett, Mr Jones decided on an immediate strategy of containment. A couple of rehearsals had to be cancelled, but the choir was committed to 15 concerts, including a live spot on BBC Radio 2's Friday Night Is Music Night, between the end of September and Christmas. In the meantime, Jessett resigned.
Parents were not told the reason for Jessett's absence until Mr Jones called a meeting and broke the appalling news. "It was an emotional meeting," he recalls. "I could not say much because we were talking about an ex-employee, but I was aware that the parents had a right to know what was going on."
A follow-up letter revealed all. Many parents refused to believe the allegations but, incredibly, none blamed the music service. It was left to parents to tell their sons.
Mr Jones made himself available to boys and parents who wanted to talk, and Manchester social services set up a helpline dedicated to MBC. The biggest concern being expressed was about the choir's survival.
Karl Berisford-Ince, father of the chief chorister, 13-year-old Joshua, says: "It was a huge shattering of trust. We had trusted Adrian Jessett implicitly. As far as we were concerned he was a great mentor and teacher and Josh looked up to him. We found it unbelievable. But because of the unparalleled opportunities Josh gets in the choir, our greatest concern was whether or not it would continue."
Mr Jones considered several candidates as replacements for Jessett, finally settling on Jeffrey Wynn Davies, who as well as being an international choir adjudicator, and director of Harrogate Choral Society and the Manchester-based Canzonetta Chamber choir, is married, with two children and a wife who also conducts choirs.
"As a package, we were a gift," says Mr Wynn Davies. "Their eyes lit up at the music service when they heard about Fiona and the boys. The family was what they needed to build up trust in the choir again."
With Mr Wynn Davies's international schedule, Fiona Clucas often has to step in to take rehearsals. She has also taken on the running of the training choirs. Their eldest son, Guy, sings in the concert choir.
"I had no particular plan," admits Mr Wynn Davies. "I was going to be reactive. We were not shoulders to cry on, we were there to do the music."
Rehearsals were not easy. Nobody left the choir initially, but Mr Wynn Davies felt resistance from a choir that was, almost to a boy, loyal to Adrian Jessett. One boy, overcome by the situation, burst into tears, others challenged their new director, saying: "This is not the way we do it in Manchester Boys' Choir."
During a rehearsal break, one lad was found gathering signatures for a good luck card to send to Jessett. On a bus journey back from a concert, a group of the older boys had to be reprimanded for displaying a window banner with the words "Jessett is innocent".
Mr Wynn Davies and his wife had a tough time of it until last autumn, when six boys left the concert choir, and a similar number quit the teenage chorus, leaving them no choice but to mount an intensive recruitment campaign. The boys are enlisted through direct contact with schools, and from regular open days and recruitment drives held by the Bridgewater Hall.
They are now almost up to strength, with the advantage of a young concert choir, only a handful of whom date from the Jessett era.
Now all the boys have sets of music, they have new silver-grey concert waistcoats and they are looking forward to a three-week trip to South Africa in the summer, when they will be guests of the world-renowned Drakensberg Boys' Choir. Rehearsals are shorter, less frequent and with an emphasis on fun as well as musical excellence.
It does not suit everyone. In private, some of the boys say the regime is too soft, and Karl Berisford-Ince says Josh "misses the discipline". But new loyalties are developing. The oldest boy in the concert choir, 15-year-old Louie Ramsden, who suffers from cystic fibrosis, turned up to a rehearsal recently with a hospital drip in his arm, having persuaded his doctors of the importance of letting him out for choir practice. He is the recipient of a new prize for commitment. Also in the choir is one lad with severe dyslexia who learns all his music by ear, and another with mild Asperger's syndrome.
The boys' pride and professional attitude is obvious, particularly on concert nights as they prepare backstage to make sure their hair and the arrangement of their music is just so. "We will give any boy aged seven to 17 the chance to sing," says Fiona Clucas. "The important thing is that they come. We are offering them a great experience - and what an experience singing to a concert hall packed with 2,500 people is."
Manchester Boys' Choir will be joining Chetham's school at the Bridgewater Hall, Manchester, on April 11 at 7.30pm for a concert that includes Pergolesi's Stabat Mater and Britten's Missa Brevis in D. Box office, tel: 0161 907 9000.For information on how to join MBC, or details of forthcoming concerts, contact Manchester music service, tel: 0161 226 4411; www.manchester.gov.ukeducationmusic
WHY BOYS' CHOIRS?
* The power and purity of boys' voices before they hit puberty is the special quality that churches have for centuries harnessed in choirs and cathedrals all over the world.
* After a period of experimentation with mixed choirs in the past 20 years, some choral trainers say mixed choirs tend to attract only girls and that the only way to persuade boys to sing is to set up separate, male-only choirs.
* Deborah Catterall, who teaches singing at Chetham's school of music in Manchester, and is musical director of the National Youth Training Choir, is convinced that if boys can be persuaded into a choir, the benefits are manifold.
She says: "Boys seem to get together between the ages of nine and 13 - there's a kind of kindred spirit and kinship of boys. Once they have had their confidence built up separately, they can get together in mixed choirs when they are older.
"Boys learn teamwork and a sense of purpose during teen years, when they most need it. They also learn discipline, respect and loyalty to a system.
That is with them for life. Any profession would benefit."
BEST IN THE WORLD
* The Vienna Boys' Choir. This dates back to 1498, when the Emperor Maximilian established the imperial chapel in Vienna. The elite organisation is divided into four separate choirs each named after a famous ex-member - Bruckner, Haydn, Mozart and Schubert. Admission to the choir and the boarding school is by rigorous audition. At least one of the choirs is permanently on tour, giving concerts round the world, while another is resident in Vienna to provide music for the imperial chapel.
* The Drakensberg Boys' Choir. Basedin the mountains surrounding the Champagne Valley in Central Drakensberg, Natal, South Africa, the "Drakie" choir was founded in 1967, with a mission to prepare boys for life and leadership through excellence in music. The boys, aged between nine and 15, regularly tour the world. They have performed for the Pope and, in 1985, became the first South African cultural group to perform behind the Iron Curtain. Entry is via competitive audition. Their concerts are divided into two halves - one a mixture of western repertoire from classical to jazz and a second consisting of African folk.
* The National Youth Choirs UK is in the process of setting up a boys'
choir aimed at trebles aged nine to 13. No experience is needed, only potential. Boys are encouraged to apply for auditions for the choir, which will have its first summer residential summer course in the Midlands in early August. For more information, tel: 01484 687023.