Titch is a project my husband and I had been working on, intermittently, for almost ten years before we were commissioned to do a series. We'd decided that the films should be model animated, and we'd already made a short promotional film, which was directed by the author/illustrator Ken Brown. Then we were very lucky to have the theme music written by Michael Nyman, the famous composer of "The Piano" theme tune.

As Titch is based on our two sons - Morgan and Sam, it's a very personal project, and we insisted on artistic control. In fact my publisher gave us the rights on condition that we produced the films. We were in the fortunate situation that Laurence, as an established film director, had a small production company through which we could work.

When I was writing the Titch books, the only other person involved was my editor. Suddenly I was co-operating with crowds - directors, animators, puppet makers, model makers, actors and commissioning editors. I was lucky, they were interesting people, and fun to work with. Laurence had to deal with lawyers and accountants as well who weren't particularly fun to work with.

Writing scripts is very different to writing books, the only similarity is that each script, like a book, tells a complete story. In a book, the timing of the story is in the turning of the pages. In filming, the timing has to be more fluid. I start with an outline script, which is then translated into a storyboard for the animators. The storyboard artist draws all the directional movements of the puppets. The animators work very closely to the storyboard. When each film is completed and edited, I do a rewrite, working from the moving images, making adjustments to the text, so the narrative flows with the pace of the film.

Peter Jones, the Narrator of 'Hitchhiker's Guide to the Galaxy', read the first two series. The reading of the series is a vital element in our concept of Titch. Paul Vaughan, the voice of BBC's 'Horizon' has now taken over from Peter. He has the same reassuring quality without being patronising, he too has that understated humour in his reading.

The puppets have to be sculpted in clay before the heads are cast in resin. The skeletons, or armatures, are made of special metals to high precision standards to withstand the variations in temperature that the puppets are subjected to, every day for nine months. Three puppets of each character are needed as the animators can be working on three different stages at any one time. The puppet maker worked from my original Titch drawings and it was wonderful witnessing Titch becoming three-dimensional.

Working with animators was a new experience for me. I felt like a possessive mother. Titch was literally my child, but they were going to be responsible for the movements and actions that define his personality. We decided that I should write a biographical piece on Titch to help them in their approach. I think it helped us all. I suppose it is because an animator can bring a puppet to "life" that they start thinking of the puppets as human. Titch is created with great care and affection. If the animators feel that something is not quite working in the animation, they've been heard to say: "that's not right. Titch wouldn't behave in that way", and re-shoot a sequence.

Budgets for children's programmes are notoriously small, model animation is very costly. It is a painstakingly slow process, for every second of screen time, the animators move the puppets at least twelve times, sometimes as much as twenty four times to achieve a natural movement.

My biggest challenge has been working with a tiny budget. In the first series, Titch couldn't have any friends visiting him. In a book it wouldn't cost anything. In a model animated film, a friend visiting could cost as much as a small car. So parties were definitely out. I had to devise a way of Titch contacting friends, so I used a telephone. Titch was constantly being told that his friends were coming over, but the programme had to finish before they arrived. The episodes had to revolve around the existing family of puppets, and the confines of their home, which was quite a challenge.

It would have been difficult to wirte another thirteen episodes within these confines. So, regardless of the budget, we introduced Daisy - Titch's best friend, into the present series. The animators have fallen in love with Daisy, they've started talking to her. So I suspect she might steal the show. But Titch wouldn't mind. Daisy is his best friend. I'm beginning to sound like the animators!