Her books have sold 12 million copies in 46 countries, so Joanne Harris isn't fazed by the prospect of facing a room of curious Year 7s.
The writer, whose best-selling book Chocolat has been made into an Oscar nominated film starring Johnny Depp and Juliette Binoche, calmly sips tea in a back room at the Astley Cooper School in Hemel Hempstead, Hertfordshire.
"I'm not nervous about what the pupils are going to ask me," she says. "I've been a teacher. And the first question I got asked was: 'Miss, what's cunnilingus?' Nothing surprises you after that."
The visit is part of the school's ambitious plan to improve pupils' reading levels with a series of inspiring talks and workshops by famous authors, with recent visitors including Frederick Forsyth and Jodie Picoult. So far, it seems to be working. In the past year, key stage 3 English results at the school have increased from 66 per cent of pupils getting level 5 to 75 per cent.
And although celebrity culture is often thought of as the enemy of education, encouraging teenagers to moon over Big Brother instead of knuckling down to their books, Astley Cooper is just one of dozens of schools which has harnessed it to its advantage.
"Once they have seen the authors they want to read the books. They all vanish from the library. And they even ask us for tips on what to read," says Susan Crawshaw, head of English.
"It has made the pupils feel very special. It's broadened their horizons and lifted the whole school," adds Anne Smithers, headteacher.
The event is organised by Karl Vadaszffy, the school's gifted and talented co ordinator. A reading and question-and-answer session is followed by a book signing and an in-depth workshop with gifted and talented pupils. Hands shoot up as Karl calls for questions. "How much money do you make?" "Are you in it for the cash or the recognition?" "Is your work autobiographical?" the pupils clamour. Then a queue snakes around the room as the book signing begins.
"I didn't read much before the writers started coming," says Calum Coe, 13, brandishing a copy of the author's latest work, Runemarks.
Booking celebrities needn't be rocket science. Whether you approach them directly, go through an established speaking agency or use and abuse personal contacts, there are ways and means of reeling them in.
Jane Waters, assistant head of Seven Kings School in Ilford, Essex, teamed up with her local bookshop to host talks and signings for authors passing through town on publicity tours.
"Pupils could see the teachers were really excited about the talks, and it made it cool to be seen reading. The library became the centre of the school," she says.
Speakers included Bali Rai, the author, John Hegley, the poet, and Michael Palin, the broadcaster and ex-Python. "He has a soft spot for teachers so he was keen to come in and the children were gobsmacked to have him," she says.
At Ashmount Primary in north London, Pana McGee, the headteacher, brought in celebrities such as the newscasters Jon Snow and Trevor McDonald to address Year 6 as part of a project to raise aspiration.
"There used to be an attitude of: 'Don't send your kids to Ashmount.' We don't have that anymore. It has raised the pupils' self-esteem and our profile in the community," Pana says.
It has also changed the attitude of the children. "They feel they have been singled out and are special. They are proud of the school now."
For Arthur Boulton, arts and industry liaison manager at the BRIT performing arts school in Croydon, which produced Katie Melua, there are different reasons to hook up with the rich and famous.
When artists such as Tom Jones, Amy Winehouse and Duran Duran drop in, they are as likely to be talking about their tax status and royalties as the glamour of life on the road.
"A lot of people who perform are self-employed and that means knowing how to take responsibility for your money," he says. "Many of them get a big advance, spend it, then the taxman comes knocking two years later. Because our pupils may go on to work in the business, we don't want them to see it through rose tinted specs."
Of course some pupils, particularly younger ones, may not always recognise the famous faces stalking the corridors. But Sean O'Sullivan, acting head of Frank Wise, a special school in Banbury in Oxfordshire, says the experience can still have value.
He booked Bobby Charlton, a member of the 1966 World Cup winning team; Will Carling, the former England rugby captain; and John McCririck, the racing commentator, to take part in a film with pupils aged from two to 16 entitled Great Sporting Moments.
"Beforehand, we showed them photos of who they were going to meet and talked them up," he says. "They could sense the atmosphere, and were completely awestruck."
They held a red-carpet premier at the local Odeon, and Sean says the celebrity involvement helped the staff raise their game. "It made us focus on making this a really great product, which made the children look fantastic and capable," he says.
Back at Astley Cooper, Karl shows me his Board of Encouragement, a massive pinboard studded with signed photos of the rich and famous tagged with inspiring quotes. At the school's request, stars including Ainsley Harriott, the chef ("be brilliant, be brave and be wonderfully creative"), John Hurt, the actor ("press on") and Henry Winkler, aka the Fonz ("don't forget you have greatness inside you") have sent in their words of wisdom.
"They write about the importance of working hard and pursuing your dreams," says Karl. "If you want to inspire pupils, these are the people who are going to help you."
GETTING THAT GUEST
Most celebrities are sympathetic to invitations from schools and won't usually charge a fee. You can approach them directly, either through their agent, publisher, record label or production company. Agency contact details can be obtained from directories such as www.spotlightcd.com or Who's Who.
If staff or parents have famous contacts, use them too.
If you can afford it, consider going through a professional speakers' agency, such as womenspeakers.co.uk or JLA, who hire out speakers for anything from pound;500 upwards. Some schools club together to afford the fees.
Go into business with your local bookshop. Some will agree to hold author events at your school on the understanding that they can run a book stall or open the talk to members of the public. Contact your local store manager for details.
SUPPORTING CAST OF CELEBRITIES
Celebrities helped to turn around a failing school in west London after it was brought to the brink of closure following the stabbing of former headteacher Philip Lawrence outside the school gates.
Cherie Blair, Frank Bruno, the boxer, Princess Anne and Ralph Fiennes, the actor, were brought in to speak to pupils at St George's Catholic School in Maida Vale as part of a project aimed at raising aspiration called I Could Do That.
"I don't like the term celebrity. I prefer to call them 'distinguished guests'," says Lady Marie Stubbs, then headteacher. "I would never invite 'slebs' into school. It is about people of quality with positive values who have made a contribution to society.
"Obviously you can't bring in Frank Bruno and transform a failing school. But we trained the pupils in how to welcome our guests properly, and how to think of interesting questions. It was an incentive to behave well. When we had Ralph Fiennes in, you could see them think: 'yes, I could do that too.'"
But lofty guests don't always have the intended effect. "Once I asked a very naughty girl if she'd enjoyed a talk by Cherie Blair. She said: 'Miss, it was dead interesting. And I loved her boots'."