I am on a mobile, talking to Paul McKenna’s mother. In the next room, a dog the size of a small pony gulps water from a bath tap. McKenna paces about wearing a jewel-studded watch. There are three teachers here too, posing for a photographer. On the other end of the phone, Joan McKenna recounts how they used to say in the family that Paul would either end up as prime minister or with a stall on Petticoat Lane market. Does he work his magic on you? I hear myself asking her. “He tries,” she replies, enigmatically.

The scenario is not the cheese-induced dream it appears. In early May, we invited Friday readers to tell us why, as job seekers, they needed a shot of instant confidence. Scores of teachers entered the competition and described (in 50 words) the fears that were holding back their careers; Paul Norman, Lynne Spencer and Harriet Dunn won the rare opportunity to have a personal session with self-help guru and hypnotist Paul McKenna.

Self-belief is a serious matter; it is what teachers spend their lives trying to give children, and is an essential quality for adults. But is “instant confidence” - the title and promise of McKenna’s new book - really possible? Our three winners had a chance to find out for themselves.

Paul Norman described himself as a “typical jock”; he was great with a ball, he said, but fell apart with a pen. The 27-year-old, a PE teacher at Dulwich College, an independent boys’ school in south London, believed he would never reach head of department, let alone anything more senior. Lynne Spencer, 43, head of art at Redruth secondary school in Cornwall, suffered from another syndrome well known in schools: she was brilliant at motivating others, she said, and even had a diploma in life coaching, but was hopeless when it came to her own self-confidence.

New mother Harriet Dunn, 35, had taken the bold step of switching sectors and retraining as a primary teacher after years of misery teaching foreign languages in secondary schools. She loved her work as a supply teacher, but her problem, she wrote, was “images of interview panels”, which sabotaged her belief that she could get a permanent job. On the first Saturday of the Whitsun half-term, all three made their way to McKenna’s house in a quietly opulent Kensington mews.

Paul McKenna rarely does personal sessions these days. He is a confidence-booster to the stars - his clients include Robbie Williams and Daryl Hannah - and he holds mass meetings. But one-to-one help is, for most people, not available. He is welcoming and friendly with the teachers, though their colourful presence clashes with the strict black-and-ivory backdrop of his living room. He appears genuinely interested in their problems and begins the session by getting them to identify what their confidence deficit is, what it is getting in the way of, and how they would feel if they achieved what they wished for. New Zealander Paul Norman describes the difficulty he has in putting pen to paper. “On the sporting side and socially, I’m very confident,” he says. “What I lack is belief in my ability to do the academic side of the job: writing reports and schemes of work, making presentations to senior management.”

Lynne Spencer talks about feeling marginalised by her management team.

Highly motivated, she started her current job wanting to make hers the best art department in the county. Now, she wants to work towards becoming a head of faculty. But she doesn’t feel like a player in her school’s senior ranks. “I would like to feel they value me, as one of their colleagues,”

she tells McKenna.

Harriet Dunn twiddles her hair as she tells McKenna she finds it difficult to envisage herself in the success-filled future he asks her to conjure. “I would feel I was developing my skills,” she volunteers, in the end. She is already a fan of McKenna’s, having successfully lost a stone with his book I Can Make You Thin. (My sister-in-law, on the other hand, found it of no assistance.) McKenna - whose bookcases demonstrate his compulsive interest in his field, packed with tomes on mind-mapping, memory, happiness and money-making - uses a range of techniques in his work. He is part salesman, part cheerleader, part magician. He is also, of course, part teacher.

He begins the session with a practice borrowed from a martial art. In this mind and body exercise (see box), he shows the three how they can literally become less of a “pushover”, teaching them to put their attention in their bellies rather than their heads, and see how their centre of gravity shifts. The teachers initially bend like bamboo when gently pushed. They start practising the technique and, one by one, become rock-like. It is dumbfounding to watch.

With their newfound gravitas, he gets them to imagine themselves in stressful situations. Lynne faces her headteacher, and feels her stress level diminish drastically, from eight to two on the scale he asks her to use.

Harriet says she feels power surging through her. “I feel like a block of steel,” she announces, and even picturing herself facing Ofsted does not faze her. McKenna gets her to imagine herself coping well in stressful situations, using his trump card, the voice, to instruct: “see what you’ll see, hear what you’ll hear and feel how good you’ll feel”. Best known as a hypnotist, Paul McKenna truly does have a hypnotic voice, deep and slithery as the python in Disney’s Jungle Book. His father and brother also have deep voices, he says, although neither has turned them to quite the account he has. The effect is spoiled occasionally as his voice slows almost to a halt and slides into the mid-Atlantic; isn’t that the voice of a jewellery salesman on a shopping channel?

Having mastered the technique, the teachers work on each other, imagining a range of scary scenarios and emptying each of their dread content. McKenna is solicitous, light on his feet as he moves around them. He dances off to his kitchen and returns with bottles of mineral water. “We’ve knocked off some of the biggies already,” he says, sounding pleased.

For the rest of the morning, he works intensively on the teachers, using strategies outlined in the book. One involves neuro-linguistic programming: all three have to remember - in full colour - a time when they felt positive, motivated and full of confidence, squeezing their fingers together as they do so. Afterwards, McKenna tells them they will be able to bring that confidence to bear in any situation, by pressing their fingers together in the same way. Another exercise involves the teachers imagining themselves in the bodies of colleagues who have the skills they wish to acquire, seeing the world through their eyes.

Part of what he does sounds like the kind of pep talk any friend might deliver. Lynne’s lack of confidence, he shows her, is not in herself but in other people. “You believe you can do this job. Your concern is, do other people believe it?” He tells Paul Norman to imagine himself as a confident report-writer, covering pages without hindrance, instead of, as currently, without punctuation. On Harriet’s fear of music teaching, he points out that teaching is about more than subject knowledge. “It’s who you are that makes the difference. You go in with enthusiasm, joy and motivation, and the subject comes alive.”

Paul gets practical techniques to compensate for his poor memory. “Your kinaesthetic memory will be phenomenal,” McKenna tells the sportsman.

Sitting on McKenna’s couch, Paul practises imagining people’s faces magnified, coming towards him, as he repeats their names, and is soon able to remember the names of everyone present plus an eight-digit string of numbers.

Harriet Dunn, who describes teaching as her “creative outlet” but who lacks self-belief, seems to change visibly in the course of the morning, her face lightening and opening, her body straightening. “I don’t know how I’ll get there but I know I can do it,” she declares, referring to the job she wants.

McKenna ends the session with something more like traditional hypnosis, getting Paul, Harriet and Lynne to relax, close their eyes and listen as he talks them back through childhood events - magnifying the good ones, blitzing the bad - and on into an imagined rosy future. Just after 1pm, he counts the teachers back into the here and now, his agent’s Great Dane bounds up the stairs, and the photographer arrives. McKenna rings his mother and hands over the phone to me, suggesting we chat about the teacher training she does at Middlesex University.

The object, for all three teachers, was to move them towards getting better jobs or permanent jobs; we advertised the competition with the tag line, “Want a new job but lack the confidence to go for it?”. Each has the offer of a telephone booster session if they need it and we plan to revisit them in the autumn to discover what changes they have made.

But back at school after the half-term break and 10 days since they saw Paul McKenna, how are they doing?

Lynne Spencer has listened repeatedly to the CD that comes with the book and has used the techniques she learned several times, going into meetings with her “new, positive, head on”. “It’s definitely going to make a difference,” she says. “I needed someone to give me that motivation, to try something new.” On a scale of 1 to 10, how does she rate the McKenna experience? “Eleven,” she says.

Paul Norman, just back from kayaking with a group of kids, is equally upbeat. He is now able to remember colleagues’ names and feels good about future job applications. “Some things sunk in, some went over my head. But I’d give it 10, definitely.”

Harriet Dunn is happy, too. “I’m coming down on misbehaviour a bit quicker, I’m a bit more on the ball. I do feel different.” Her approval rating for McKenna? “I have to give it 10. It’s a bit crap to be uncritical but I need practical techniques and he’s very practical. The whole experience has stayed with me.”

Paul McKenna describes the aim of his work as getting people to “make a new generalisation” about themselves. “They were all rehearsing failure again and again, imagining being negatively judged. I was quite happy they were changed significantly by the end of the session.”

He freely admits the book is a quick fix, has a dislike of traditional therapies and believes his techniques “work most of the time, for most people”. McKenna, by this time, is talking from his hotel room in Los Angeles. He has a date tonight, and has been feeling nervous about it.

Really? “I’m not saying don’t have fears and problems,” he says. “It’s how you approach them that matters.”