Lizo: So King's Cross, all those people, all those press -- what an amazing reception!

It was wonderful. It was the best. All those children, it was wonderful.

Is this the best part of doing publicity for a book like this, going round the country meeting everyone?

My favourite things are writing, then when you have to do the odd promotional bit, meeting children is by far my favourite thing. It's wonderful. And the not so young children too!

What's the weirdest thing a child's ever asked you at an event or signing?

The most starting things are when children ask me questions which reveal they're following my thought processes a lot more closely than I would have guessed. There was a boy who asked me in San Francisco before Book Three appeared, where did Scabbers come from, what's his history? For people who don't know, Scabbers is a rat who turns out not to be a rat at all; and I found it quite spooky that he'd homed in on that, because I'd known from the first book that he wasn't a rat. I think children are reading the books twelve times, and they're really starting to know the way my mind works.

Is that a danger with the internet?

The Internet! Twice I've been on the internet. Friends of mine were telling me what's on there and I'd never gone looking before. First time, I thought I was never coming back, it's too scary. Some of the stuff that's out there is very weird. Second time I went in there someone had set up an unofficial fan site where you can be sorted, they have a Sorting Hat, and I was Hufflepuff. I wasn't that pleased! If anyone's meant to be Gryffindor, it's me.

Do you find there's a worry that you can say one thing in a conversation somewhere and something else in an interview and these people will draw conclusions that are close to what you're doing to do in the books?

Mostly, people have put together something I've said, something they'd like to think I'd said, and something that someone else has said which was completely false, and drawn completely the wrong conclusions. That just happens. No one yet has guessed what's going to happen, or come anywhere close.

Now, Book Four. Very scary ending. How difficult was it to write that?

The first time ever, I cried while writing. I actually cried twice during the ending of Book Four. It's a powerful ending, but there's a reason why - something VERY important happens. I have said all along that if you're writing about evil you should have enough respect for children to show them what means. Not to dress up a pantomime villain and say, isn't it frightening?, when it isn't. It's the ending I planned and I was very happy when I re-read it.

Do you rewrite a lot?

A huge amount. Only once have I said down, written something end to end, and let it stand. That was the chapter in Philosopher's Stone when Harry learns to fly. I remember vividly -- the old story we've heard a million times -- my daughter fell asleep, it was a beautifully sunny day, I sat in a café, and wrote that chapter from beginning to end. And I think I changed two words. That's very unusual for me. I think there's a chapter in Book Four which I rewrote 13 times. At one point I thought this book would never happen.

And how vital is Book Four in the 7 book series for Harry?

Crucial. Book Four's a very very VERY important book. Something very important happens in Book Four. But also, it's literally a central book. It's almost the heart of the series, and it's pivotal. It's very difficult to talk about all seven books. I can't wait until the day when someone's read all seven and I can talk completely freely about them, but it's a very important book.

I know you write for yourself, not for a target audience, but it must have some effect, the expectation and pressure that's built up around Harry.

Actually the expectation doesn't bother me at all - because I do my readers the justice that they want to hear the story I want to write. If they've stayed with me for three novels, I hope they just want to find out what happens next, as I see it. There are other pressures with having a successful book, like Azkaban. That was difficult at times. But the weight of expectation doesn't bother me.

Book Four explores several themes - some we've seen before like prejudice in Chamber of Secrets. We see more of that with foreign students and people with different parentage. Is that something you've been wanting to explore?

From the beginning of Philosopher's Stone, prejudice is a very strong theme. It is plausible that Harry enters the world wide-eyed: everything will be wonderful and it's the sort of place where injustices don't happen. Then he finds out that it does happen and it's a shock to him. He finds out that he is a half-blood: to a wizard like Lucius Malfoy, he will never be a true wizard, because his mother was of Muggle parentage. It's a very important theme.

Voldemort's a half-blood too.

Like Hitler! See! I think it's the case that the biggest bully takes their own defects and they put them on someone else, and they try to destroy them. And that's what he -- Voldemort -- does. That was very conscious -- I wanted to create a villain where you could understand the workings of his mind, not just have a 2-D baddie, dressed up in black, and I wanted to explore that and see where that came from. Harry in Book Four is starting to come to terms with what makes a person turn that way. Because they took wrong choices and he Voldemort took wrong choices from an early age.

Was it difficult balancing the light and dark in the book - you've got some dark moments, and some wonderful moments of humour. Mad-Eye Moody who can't tell the difference between a handshake and an attempted murder. And a slightly dodgy joke about one of the planets in solar system.

Yeah, slightly dodgy! I was glad my editor let me get away with that joke, because she really laughed. Is it difficult? No. My experience is that, in a very limited way, even when life is not that bright, people still laugh. In the most tragic situations. The ending of the book is very important to me because Harry says, we're going to need some laughs. That is what so admirable about human beings because even when they're in the direst situations, there's still humour.

Why was it important to show some of the strained friendships developing in this book?

Well in Book Four for me, Harry, Ron and Hermione are all starting to find their own identities - that means, in their various ways, facing up to what their parents have imposed on them, or the school. For Harry, that's facing up to fame, really facing up to it for the first time. He's been put into a situation where for the first time he'll get the weight of outside interest. So that's scary. Ron has to deal with his jealousy. He's made friends with the most famous boy in the year and that's not easy. And Hermione gets a political conscience. Yeah!

Is this your idea of Hermione lightening up as you've said before. She didn't seem that light to me.

No, she will! She's a good girl. I agree with you -- she's not that light in this book. But people made the mistake of assuming that my answers referred to Book Four. There are another three books to go. But in some ways -- she's more of a rule breaker now. Where her convictions are concerned, she's prepared to do stuff that she's really not supposed to do. But she will lighten up. I promise you. I did.

Last time we spoke you said there'd be a Weasley cousin. It didn't appear. You've deceived me!

It got pulled. Sorry about that. What happened on Book Four, and one of the reasons why it was easily the most difficult to write, which had absolutely nothing to do with Harry being famous or me being famous, was that for the first time my plan fell down. I got halfway through and realised there was a huge gaping plot hole. The two ends just didn't meet. It was entirely my own fault: I should have had the sense to go through it very carefully before I started writing. So I had to do an enormous amount of unpicking and in the process I'm afraid the Weasley cousin disappeared.

Will we see her again?

Possibly. I really like her as a character but it's quite a complex plot I'm dealing with so I'm not sure that she'll fit anywhere else. She'll be the "character that might have been."

It's quite appropriate we're talking to you on a train - King's Cross, your parents, the whole Harry story.

I love trains - I wouldn't be here but for the fact that my father managed by the skin of his teeth to get a train from King's Cross - that's where he met my mother; he proposed to my mother on train and I got my idea for Harry Potter on a train. Fairly appropriate.

Are you tired of being asked where you got Harry from?

Yes. I get frustrated with myself because you'd think by now I'd have an intelligent or amusing answer to that question, but no I haven't found one yet! The truth is, I do not know where he came from - he walked into my head, fully formed, a scrawny little boy, and I knew he was a wizard and I knew he didn't know he was a wizard and I worked backwards from there. I felt this incredible upsurge of excitement about writing the story.

Are you worried there will be a British-style backlash against Harry?

That happens. Obviously I've only very recently had any dealings with press or television. I've seen that happen to people I admire. To an extent, I expected it to happen on Azkaban, but didn't happen, so I'm due it.

There's a character in this book, Rita; how true is this a depiction of your relations with the press?

Well I'll tell you the truth but I doubt very much that anyone's going to want to hear this. I tried to put Rita in Philosopher's Stone -- you know when Harry walks into the Leaky Cauldron for the first time and everyone says, "Mr Potter you're back!", I wanted to put a journalist in there. She wasn't called Rita then but she was a woman. And then I thought, as I looked at the plot overall, I thought, that's not really where she fits best, she fits best in Four when Harry's supposed to come to terms with his fame. So I pulled Rita from Book One and planned her entrance for Book Four and I was really looking forward to Rita coming in Book Four. For the first time ever, my pen metaphorically hesitated over writing her, because I thought, everyone will think this is my response to what's happened to me. But the fact is, Rita was planned all along. Did I enjoy her a little more because of what's happened to me -- yeah I probably did!

A little more venom in her?

Venom? Would you say so??! No -- I wouldn't call it venom.

Now the future - Lupin comes back in Book Five.

You see Lupin in Book Five. Do you like him?

Lizo: Yes, he's one of my favourites.

And me. I always looked forward to writing Book Three because of Professor Lupin. I love him. Yes you see a lot of old characters in Book Five. Yes. I'm not even going to tell you what happens in Book Five! I'm just recovering from the stress of Book Four!!

And how are we with the film?

It's ongoing. We still haven't got Harry, which is a bit of a worry. I've seen some things and they look incredible. I'm very lucky - I've been given a lot of input into how I imagine things and they're really trying to recreate how I see things in my head, and it's the most amazing to see Quidditch, or Hagrid's hut, stuff you've just been watching in your head for ages.

Does it annoy you sometimes when the press and people just talk about children's books and they only talk about Harry Potter, without realising there's a whole wealth of other children's books out there?

Yes it does. Yes it really does. Children's books have existed for quite a long time in press terms in a bit of a ghetto, when you look at the coverage adult books get. You hope that that might change. People say to me, adults read Harry Potter as well, so it's this big crossover book; but loads and loads and loads of children's writers deserve to be read by adults. They might not be quite as famous for it as Harry is, but there are people like Jaqueline Wilson, David Almond and Aidan Chambers who just won the Carnegie. Henrietta Brownford I really admire, though she died unfortunately two years ago. There are loads of people out there - Philip Pullman too -- wonderful writers.

Now in an interview you said that Firenze, the Centaur, was based on a friend of yours -- but we've hardly seen anything of Firenze.

Well, just keep your eyes open.

And the Centaur's Prophecy at the end of Philosophers Stone.

He'll come back -- enough said. Not everyone has read book four.

And Gilderoy Lockhart, one of my favourite characters.

Gilderoy, bless him, is still in Saint Mungo's hospital for magical ailments and injuries, 'cos his memory's just gone. So I'm making no promises about Gilderoy.

Was he good fun to write, because he's the opposite of everything you wanted to be?

Fantastic fun to write. The best one ever. I loved writing Gilderoy, but I've got Rita now you see. I love writing Rita in the same way that I loved writing Gilderoy.

Does the whole merchandising that's about to kick in worry you slightly -- are we actually going to see Gilderoy Lockhart hair care products.

I think that would be quite funny actually. Does it worry me? Yes it does in all honesty, yes it does worry me. Erm, it's going to happen, that's what happens with films -- there will be merchandising. I have seen early examples of the sorts of stuff they're doing and I have no objection to it at all. Erm, but it does make me jumpy, yes it does. I don't want to, I don't know, no.

Now we've seen hormones kick in in this book. Are we going to see Harry becoming even MORE like Kevin the teenager, you know, [does Kevin impression] 'Sirius, huh, I hate you, I wish you were back in Azkaban'?

I think Ron's more like that isn't he? Ron's more Kevinish. Harry's got so many worries, he needs his friends -- he can't afford to alienate them.

He's delicate isn't he?

He is. He's more your sensitive hero. And more of that stuff happens.

Now, can I ask you: are there any special wizarding powers in your world that depend on the wizard using their eyes to do something? Bit like.

Why do you want to know this?

I just vaguely wondered.

Why?

Well because everyone always goes on about how Harry's got Lilly Potter's eyes?

Aren't you smart? There is something, maybe, coming about that. I'm going to say no more. Very clever.

And I'm going to ask one other question which you'll say isn't clever at all. The significance of the place where Harry and his parents lived, the first name -

Godric Gryffindor. Very good, you're a bit good you are, aren't you?

Thank you.

I'm impressed. My editor didn't notice , I said to her haven't you noticed any connection between where Harry's parents were born, not born, where they lived and, one of the Hogwarts houses and she's sitting there going erm, I'm not being rude about Emma, she's brilliant editor, the best I've ever. But know she didn't pick that up either. You're a bit good you are.

Oh well, that seems a wonderful time to stop while I'm ahead. Thank you so much for your time.

No problem, I've enjoyed it.