Close your eyes and think of a Children's Laureate. All three so far have had an essential quality that sums up their laureateship besides their impeccable records in children's literature. For Quentin Blake (1999-2001) it was the drawings that placed the visual impact of books at centre stage; for Anne Fine it was the stacks of much-loved books she urged children to acquire and customise; and for Michael Morpurgo, the outgoing laureate, it has been places: the wild settings for his books, the English and Welsh countryside he supports through his Farms for City Children charity, and the far-flung schools he has visited over the past two years.
Think of Jacqueline Wilson, appointed the fourth Children's Laureate yesterday, and the picture that comes to mind is simply of children, lots of them: queues of young people snaking around bookshops and literary festival tents; children carrying home her books four at a time from public libraries, where she is the most borrowed author (two million loans last year); TES Write Away winners meeting her at the Shakespeare's Globe presentation (she is in her third year as a judge, and has been reading entries during the busy run-up to becoming laureate).
In the books themselves, there are children with troubled lives and hopeless parents, but also children with courage and wonderful friends, and sometimes (as in her latest novel, Clean Break, and Midnight, of which a play version can be seen at Richmond Theatre in London) children saved by their love of books. Mostly, but not exclusively, girls of eight to 12, Wilson's fans write letters by the sackful, an average of 200 a week: in the latest gel pens (gold, scented, rainbow); in Braille; on Jacqueline Wilson notepaper; or on sheets from homework pads adorned with stickers or drawings of themselves with the author. They never forget to include her big rings and funky haircut, but they often draw her in Doc Martens and dungarees when these days you are more likely to see her wearing dainty pumps with pretty, floaty and slightly Gothic skirts and dresses. She keeps the recent arrivals from her publisher (and those addressed to "Jacqueline Wilson, author, Kingston upon Thames") in a wicker basket which she gets out for up to two hours every evening, even when she's been to the Whitbread awards dinner or her party at Claridge's to celebrate 20 million sales (close behind the one at the Ritz for 10 million sales).
"It's really frustrating, but I can't - I physically can't - reply to them all," she says. "I like to read them all, and I reply to those who have done something really special. I try to reply to a child who is ill or upset. Every time I feel overwhelmed, a really lovely one comes along and I think, 'I must keep doing this'.
"This child I've just replied to called Brontey - I don't know if it's a boy or a girl - has written a story called 'One Mum, Two Mum, Three Mum, None' about a boy whose parents split up and his dad keeps getting different girlfriends. It's very touching." One correspondent from France who might or might not get a reply ("I might not be your No 1 fan, maybe just your No 5 fan") advises her not to grow her hair long now it is grey, or she will look more like a witch than a princess. The flowery border on the notepaper softens the blow.
They send hand-made cards, photographs of themselves in hospital clutching a book, jacket designs inspired by Nick Sharratt, whose illustrations are now an indelible part of the Jacqueline Wilson experience. Some send stories they've written or outlines of books they promise to write in the holidays and send to the author for her comments. Two best friends from south London, girls aged 12 and 13, write regular colour-coded letters (one uses a red felt tip, the other mauve) finishing each other's sentences and drawing flattering portraits of each other as they deliver updates on the progress of their book. They're on page 130.
Lauren, who has drawn a poster for the "Best Author in the World" ("please, please, pretty please with sugar on top, hang it on your wall") is a local fan and wants to know when her heroine is coming to Kingston library again.
It could be sooner than Lauren thinks. Jacqueline Wilson has lived mostly in Kingston since she was five; she has had her eye on her new house since she went for childhood walks with her grandmother ("she always said it was her favourite"), although the library for her 15,000 books in the neighbouring former dentist's surgery is a recent plan. Her celebrity status has not stopped her going for her daily swim. "It's the most delightful half and half. I'm not like the Beckhams and I mostly lead a perfectly ordinary life, but every so often I find myself surrounded by children, especially at half-term. It's lovely and I don't mind a bit. I have been twice pursued into ladies' rooms and just once a kid put her head under the toilet door and I had to tell her to go away."
Perhaps it's just as well that she did not take a loo break at her now legendary signing session last year in Bournemouth (eight hours non-stop and more than 1,000 children). Now her signings are all ticketed ("It was too long for children to wait"), but she never wants to stop meeting the readers en masse. "It's how I find out what they care about, and keep up with the fashions. It's as if I'm two people: I'm me and I'm this person who makes children say, 'Wow, it's Jacqueline Wilson'."
It's the me-person rather than the Wow-person who was the laureate committee's widely anticipated choice for the post, which recognises significant lifetime achievement. The Children's Laureate has a handful of annual official engagements, but otherwise is simply expected to be an advocate for children's literature and can pursue whatever personal projects they wish to further that aim. For Jacqueline Wilson the role will run alongside writing her usual two novels a year and supporting organisations such as Right to Read (which campaigns for more audio, Braille and large-print editions of children's books) and the Fostering Network, for whom she has just launched Foster Care Fortnight.
The real-life children behind The Story of Tracy Beaker, her 1992 breakthrough book about a much-fostered child (more than a million copies sold with a fifth BBC TV series on its way this year), are close to her heart. "Tracy tells it like it is. She has a lot of attitude and she isn't always fair to the adults who try to help her, but she has a happy ending.
I want the real-life Tracys to have a happy ending."
Her first career as a magazine journalist in the Sixties has made her highly organised and immune to writer's block. "I'm good at multi-tasking and using pockets of time to write. I take my notebook everywhere." There are shades of the Anne Fine approach to the laureateship in her statement that, "I have to think about what children need, which might not be what they want." With her Home Library bookplates scheme, Anne Fine championed children as active, book-hungry readers and urged them to pester librarians and search second-hand bookshops for the hard-to-find titles they wanted; not to give up easily; not to wait for the right book to come along.
Jacqueline Wilson, who in Clean Break introduces herself as the bestselling "Jenna Williams", idolised by children but mildly puzzling to adults (when did you last see a grown-up reading a Jacqueline Wilson?), has been known to use her storylines to nudge her readers towards books that she thinks will stretch them, from Louis Sachar's Holes to classics such as Little Women and What Katy Did. "It's delightful that children want to read my books but I do want to give them a stepping-stone to something else. I can imagine their teachers saying, 'Not another Jacqueline Wilson'. Even the most dedicated child bookworms don't read the wonderful children's classics that once everyone of a certain age read. Just looking at the small print and the illustrations makes them say, 'Oh, boring!' " She imagines child-friendly new editions, "with really good covers, an introduction by a celebrity and encouraging notes in the margins. Something like, 'there's a really good bit coming' or 'you must read this next chapter'."
She is taken with a project in Poland in which schools, nurseries and children's hospital wards commit to reading aloud for 20 minutes a day.
"That's how children get hooked for life. You can't stress the joy of reading aloud too much. I can see it working at home too, for children up to about 12. Even when you are busy, 20 minutes is manageable and it's a perfect length for the child to catch the excitement of the story." And she hopes to give the classroom author project, sometimes a sad ailing creature, a new lease of life with a touring exhibition on the work of current authors and illustrators, featuring work in progress and memorabilia as well as the authors' own questions for children to explore.
She despairs when children proudly show her projects that they have simply printed off her publisher's website. "What happened to looking in lots of different places for information, thinking for yourself and saying it in your own words?"
The letters that show evidence of this are most likely to get replies; the standard author project letter, "where the teacher has clearly told the whole class to write to lots of authors", tends to languish near the bottom of the wicker basket. She worries most that when children ask where she gets her ideas from, they don't understand the answer. "I used to say it's like when you play pretend games, but I've realised that most children don't do the pretend imaginary games that were current when I was at primary school, when you might pretend to be the Famous Five, or before that when you would dress up or play under the table. You need unstructured time for it. And I read somewhere that teachers were having to teach children to play traditional playground games. It's so sad, it's real deprivation."
If she can tackle that, adults too will be saying: "Jacqueline Wilson - Wow!"
* We have 10 tickets for TES readers to see Jacqueline Wilson in conversation with Poet Laureate Andrew Motion on September 28, just before Children's Book Week. The event, which starts at 5pm at a central London venue, is otherwise invitation-only. Please apply by June 30 to Emma Phillips, Booktrust, Book House, 45 East Hill, London SW18 2QZ. See www.childrenslaureate.org for future events. The Children's Laureate post was set up in 1998, having been backed by the late Poet Laureate Ted Hughes, and is now sponsored by Ottakar's bookstores with support from the publishers Random House, Egmont, Oxford University Press, Puffin and Walker Books, plus David Higham Literary Agency. The selection panel represents booksellers, librarians, academics and critics, and considers votes from the public, including children.