It may be the greatest film series of all, but do we need a fourth instalment? A trip to Pixar reveals why they (quite rightly) say yes. By Jonathan Dean.

I love Italian food!" bellows Tim Allen, voice of Buzz Lightyear, down the phone at me. He says a lot of random things during our chat, about the time he raced Ford cars, for instance, but this outburst quickly comes to make sense. "I know several Italian families, and they have a meal that starts pasta, bread, vegetables... then you eat. It is never-ending flavour — and that reminds me