Eleanor Walsh bounces in her seat, her long hair bouncing with her. “The longer you wait, the more nervous you get,” she says. “But my family has been supporting me, listening to me, stopping me from having a nervous breakdown.” She pauses, eyes wide. “I’m a very dramatic person.”

In the seat behind, Marie Brooks nods encouragingly. “Winning is definitely very important to Eleanor,” she says. “And to the school, actually.”

Ms Brooks is assistant principal at Capital City Academy; her pupil, 14- year-old Eleanor, is one of 15 regional finalists from across the north London borough of Brent, competing in the Jack Petchey Speak Out Challenge.

More than 20,000 Year 10 pupils from across London and Essex have taken part in the annual challenge, delivering a three-minute speech on a subject of their choice. The competition inspired the BBC reality series The Speaker, which put thousands of teenagers through their oratory paces to find Britain’s best young public speaker.

“We went on the Speak Out Challenge website and watched videos of last year’s winners,” Ms Brooks says. “Eleanor’s every bit as good as the winners from last year. So I’m quite confident, yes. We feel she has a good chance of winning.”

“I’ve written my speech over and over and over again,” Eleanor elaborates. “I just wasn’t happy with it. But then I just thought, `what comes naturally will come’. I’m more of a spur-of-the-moment person. If I feel it, I’ll say it. If you were having a conversation with people, you wouldn’t memorise lines and have it all prepared. So I’ve just got a few basic lines. But” - she pauses for breath - “everyone here is really good, so we’ll see.”

“Stop!” the evening’s MC interrupts, grabbing the microphone at the front of the room. Everyone turns to look at him, and then carries on exactly as before.

“Stop!” he says again, this time louder. And, having told them to stop, he now encourages them to start - to start clapping, to start enthusing, despite the unwelcoming chill of the large school hall. The 15 teenagers in the front row watch him with an air of slight bemusement.

Each one of them has already beaten other pupils at their own schools in order to make it into the regional final. Mohammed Abboud had not even planned to enter: the first he knew about the competition was when a teacher at Alperton Community School called out a handful of names in assembly and asked those pupils to stay behind. “I thought I was going to be in trouble,” Mohammed says. “I started thinking about the things I’d done in the last week. Then I looked around at the people I was with and I thought, `I’m not going to get in trouble. I’m with the good people.’”

Asked to deliver a speech on a subject he cared about, Mohammed had “a total mind-block”. Then, he says, “something came to my mind: terrorism. Islamic terrorism. I hear so much in the news about how we’re all terrorists, and I don’t like it.”

At school, he says, friends often make jokes about his presumed fundamentalism. ”`Oh, you’re going to bomb the whole place’, they say. You smile and laugh because they’re your friends, but it hurts. It really hurts inside. And you can’t do anything because they’re close friends, and they’re joking around with you.

“I really want to win here because if I win I can rest. I can know that my point got across to the judges. It’s not about prizes - it’s about getting my point across.”

The Brent regional final is being hosted by Crest Academy, one of the competing schools. It has been a stressful day at Crest. Earlier, the electricity blew on the first floor, and pupils are now being shepherded to the toilets by candlelight. The temperature in the hall has dropped all day, eventually plateauing somewhere just above zero. Outside, stray flakes of snow drift to the ground.

Inevitably, some of this stress has rubbed off on the Crest Girls’ Academy entrant, 14-year-old Razieh Mohammed. As other contestants nibbled on pizza and biscuits, Razieh merely eyed the trays of food suspiciously. “I am a bit nervous, sort of,” she says now. “Butterflies in my stomach. I’m scared I might throw up.”

Razieh, like Mohammed, has chosen to speak on a subject that affects her personally. “Right away, the first thing that came into my head was Afghanistan and the war - how it’s not portrayed correctly in the media,” she says. Razieh’s parents came to Britain from Afghanistan in 1990; she was born in London. “When I ask my mum now about times like that, she gets very upset. She left all her childhood memories there; she’s adapting to a life she doesn’t want to adapt to.

“So I’m using personal experience about my mum and dad and the war, and how they’d never, ever wish it on anybody and stuff. A lot of people told me to rehearse it - to get it right, word for word. I disagree. A topic like this, you can’t learn it off by heart - it has to come from the heart.”

“Stop!” the MC says again, yet louder this time. Tigger-like, he bounds from one side of the hall to the other, addressing the audience. Tealights line the stage, in case of further power cuts; audience members huddle against the pervasive chill. Perhaps the MC’s bouncing around has as much to do with raising body temperature as spirits.

He explains the evening’s rules and the criteria by which speakers will be judged. “Is eye contact good? Is delivery good? Do they grip you? Do they give you a new idea? Do they challenge you?” Then he bounces to the side, and lets the contestants take the stage.

Mohammed is first. “That’s really what I dreaded - being first,” he whispers. “When people go before you, you know what to improve. But I’m going to be the one that people look at first. I could get everything right, or I could do everything wrong, which is a bit scary.”

On stage, he gazes out at the audience, and swallows. “I’m a Muslim, and I’m about to bomb this whole school down,” he begins. “Ridiculous? Yes. Believed? Yes.”

Mohammed’s speech is sprinkled with the tricks of the secondary school debater: the dictionary definitions and the rhetorical questions. Eventually, he hits his stride, and there is a rhythm to his words. But then he catches sight of the audience and wavers. He recovers quickly, but it is too late: he and the audience have lost their momentum.

The MC bounds onto the stage as soon as Mohammed finishes, and the audience responds with a round of applause. Mohammed sinks into his seat. “Now I can relax,” he says, his jaw clenched.

Next to him, Mina Kazmi, his head of year, smiles proudly. “It’s been really hard, actually,” she says. “He’s been very nervous and he’s had to build up his confidence. But it’s a skill, public speaking. It’s knowledge that you have for a lifetime, for university interviews, jobs, work experience. The ability to speak to people, rather than at people, the ability to project yourself - that’s a real attribute. You take those things with you, don’t you?”

Next up is Thivya Jeyashanker, from Kingsbury High School. The title of her talk - “you are what you wear” - flashes up in large letters on the screen behind her. “Put your hand up if you own a hoodie,” she begins. Audience participation, like dictionary definitions, is one of the cornerstones of high-school debating.

So, too, are the personal anecdotes used by various contestants, to greater or lesser effect. Thivya, for example, talks about boarding a bus wearing a hoodie: a fellow passenger deliberately moved her handbag out of her reach. “I spent the whole journey totally uncomfortable,” Thivya says. “I felt like a dirty person.” Later, Arman Hussain, from Crest Boys’ Academy, attempts to demonstrate the invidiousness of mass-media stereotyping with this: “Even though my granddad’s gone, he was a cool person.”

He is followed by Farah Salman, from Queens Park Community School. There is a trend among contestants to give their speeches somewhat esoteric titles: “Let’s talk”, or “I have a secret”. Farah’s is entitled ” Fact or fiction?”. Actually, her talk is about a single fact: her family’s escape from war-torn Iraq. She, too, uses personal anecdote, but there is unequivocal power here. “I still hear the ringing of the sirens at night,” she says. “They still come in my nightmares.”

Razieh follows immediately afterwards. In her seat, she chews on her lower lip thoughtfully. “The thing with me is that nerves help,” she says. “When I’m nervous, that’s when the best things come.” And she marches up the stairs and onto the stage.

“Hot. Cold. Freedom. Equality. Education. And a community,” she says. “I’m talking about Afghanistan: my country, my homeland, my Afghanistan.” Very quickly, she becomes visibly impassioned. She waves her right hand at the audience; her eyes focus on a point at the back of the hall. “We’re a playground to them: play with our country, kill our people, and then leave us alone.”

Her mother, she says, describes Afghanistan as a land of green fields and bucolic joys. Her eyes redden; she focuses more intently on the middle- distance. “The exact place that my mother describes as a green field, I saw as a mass grave,” she says. Her voice catches with emotion. “You guys need to understand that mankind needs to end war, before war ends mankind.” There is a pause, like suspended breath, before the applause kicks in.

Razieh’s face melts into a grin. “Obviously, my mum cried in the audience,” she says as she takes her seat. “I told her not to because she’d make me cry. They’re going to think I went for the sympathy vote. But” - she inhales deeply - “I did everything I could. I think I’m pleased with how it went.”

Then there is a break. Eleanor has to sit through a school-band performance before she can deliver her speech, on the corrosive effects of technology. It is the final stage in a process that has already lasted months. “The first couple of weeks, I was just playing around with ideas,” Eleanor says, all raised eyebrows and expansive hand gestures. “Then, recently, I’ve been trying to structure them, so they make sense.

“Also, I’ve been doing research about how to make it more interesting and challenging, instead of boring. Two or three people have the same topic as me, so there’s added pressure. You just have to make yours better. Mine really needs to stand out.”

The band finishes its set and Eleanor squeals in her seat. “More talent than X Factor, eh?” the MC says. Then he steps aside, and Eleanor takes the stage.

She stands there and does not speak. There are one or two expectant giggles. Poised, playing the audience, Eleanor paces up and down, looking slightly peeved. “TVs,” she says, finally. “MP3s. Facebook. These evil substances are consuming the minds of innocent people. We’ve even spawned a completely new language, full of OMGs, IKRs, LOLs, ROFLMAOs.” Another pause; some more expectant laughter. “I take it you understand.”

Eleanor’s words are slow and measured. She is entirely at home onstage: in complete silence, she mimes two friends meeting in the street and communicating solely by text message. “You can either be the mindless, gormless drones of the modern era,” she concludes, “or join me in the detox from mindless technology.” Then she curtseys to the audience and skips down the stairs.

“I freaked out halfway through,” she says, returning to her seat. “I guess it was a mixture of nerves and adrenaline. I’m just proud of myself for making it through the speech.” But she surveys the row of contestants with the magnanimity of someone who knows she has done well: “Everyone had something to say, so I’d be happy if anyone won.”

There is a change of subject briefly, as the next contestant speaks about arranged marriages. Another uses the topic “Differences” as an excuse for a romp through cultural stereotypes. “If you’re Polish, you’re a builder; if you’re Muslim, you’re a terrorist. And if you’re Chinese, you’re a DVD- seller.”

Nicoya Morrison, from the Convent of Jesus and Mary Language College, takes up Eleanor’s anti-technology gauntlet: “I know if my house was burning down, the first thing I’d do is update my Facebook status: `I can’t talk right now - my house is burning down’, wait for someone to `like’ it, and then run.”

The same topic is also tackled by Chante Joseph, from Crest Girls’ Academy. Chante’s argument is less coherent, but her phraseology is striking. She talks about “retreating into the technological fortress of anti-social behaviour”, argues that “all musical morals have been eradicated”, and bemoans “the utter demise of intelligence”.

And then it is over. Adrenaline spent, the school hall feels colder than ever. When two of the judges step onto the stage to hand out certificates, they are wearing duffel coats and scarves. “You were all brilliant. Most of you were brilliant,” one of them tells the contestants. (“Most of you?” Eleanor breathes hurriedly.) Then they remove their gloves for long enough to hand out the prizes. Third prize goes to Farah, the Iraqi refugee. In second place is Chante, the articulate technophobe. “I love you, Chan!” someone calls from the audience.

And then the judges come to the winner. The contestants are still; the audience unhuddles slightly. “Razieh Mohammed,” the judges say. Razieh bursts into an utterly honest grin, then once again looks as though she might cry. “I’m thinking about my mum, and how happy she’ll be,” she says. “The competition was so good, I thought, `Well, if I’m not second or third, then I’m not first’. And then they announced my name and - oh, God.”

She will now go on to compete in the grand final, to be held in central London in July. “Obviously, the passion got through,” she says. “It’s a bigger victory because it’s so personal.”

Mohammed too looks as though he is about to burst into tears. “It was a really nice, enjoyable evening, wasn’t it, Mohammed?” asks Ms Kazmi. Mohammed nods grimly. “I really don’t feel bad,” he says. “Somebody better than me won, which they deserved. Their speech came from the heart. And my point got made, so it’s OK. The definition of a terrorist got out.”

At the opposite side of the hall, Eleanor has been surrounded by teachers and family. “I thought maybe you would be second, at the very most,” one says. “I mean, you changed the whole competition when you were up there. You were in a completely different league.” Around her, others nod: “She was robbed, wasn’t she?” Eleanor’s cheeks are suddenly very red; she says nothing as she packs up her bags to leave.

The hall is nearly empty now. A woman in hijab emerges from the back and enfolds Razieh in an enormous hug. On stage, tealights still burn, their reflection flickering in the mother’s and daughter’s eyes.

Jack Petchey’s 2011 Speak Out challenge is available to every state secondary school in London and Essex. Regional competitions will continue until June. For more information, visit www.speakoutchallenge.com.