La Tour D'Argent in Paris, The Factory in California . . . just to get the detail right for gourmet dishes served up by a cartoon rat with a nose for good food.

"I suppose there are worse jobs in the world, " Bird admits.

His dedication has paid off.

Apart from unprecedented critical acclaim in the US, where it has grossed over $200m, his comedy Ratatouille . . . arguably the greatest of all Pixar films . . . has the French in raptures, and this despite jokingly bowlderising the pronunciation of a great Provencal stewed vegetable dish from RA-ta-too-ee to RAT-atoo-ee. The venerable Le Monde newspaper hailed it as "one of the greatest gastronomic films in the history of cinema". George Bush may have demonised the French, renaming French fries as "freedom" fries, but thanks to Bird's innovative brilliance all that now seems to be forgiven.

"There you go, " he says, "and they're a tough crowd."

Never has computer-generated animation looked so sensual. It's not just the mouthwatering food;

Bird has given Paris a gorgeous, seductive look, evocative of Impressionist painting. Even the rats . . . and there are swarms of them . . . are appealingly tactile.

Dammit, they're even lovable.

"They're not that realistic, " says Bird. "They do have big cartoon eyes. But we tried to capture the way they move. We tried to make them have weight and to feel their fur. Because even if you're telling a preposterous story, the more well-observed elements you can get in there, the more it makes the fantasy believable."

Having distributed Pixar's first six movies . . . Toy Story, A Bug's Life, Toy Story 2, Monsters Inc, Finding Nemo and The Incredibles . . . Disney under new boss Bob Iger last year bought out the groundbreaking studio for $7.4bn. Its founders, Apple Computer boss Steve Jobs, Ed Catmull and John Lasseter, joined the Disney board.

Lasseter, its creative genius, was given charge of all Disney animation. Disney stock value, which had slumped after previous CEO Michael Eisner fell out with Jobs, has since soared 42%, with profits up 79% to $2.93bn in the first half of 2007.

Being under the Disney umbrella has given Pixar animators even greater freedom than they had. "If one of our films doesn't work it doesn't impact as it would have if we were independent, " says Bird. "That said, there's a tremendous amount of pressure, particularly from the financial press, to justify the Disney purchase of Pixar and that stuff I just find myopic and ridiculous. Because if we start thinking about that then we are going to drop the ball as quick as you can say Bob's your uncle. Our goal simply should be making movies that we ourselves want to see. . . It's more emotion and instinct than piecharts and ridiculous stuff like every film having to make more money than the previous one or it's not worth doing. So our job is to just stay excited."

It's tempting to equate Bird with the character Remy the rat who, with hilarious ingenuity, rises from the sewer to fulfil his dream of running the kitchen of a five-star French restaurant. "You mean, because I'm argumentative too?" laughs Bird, 50 last month.

According to Craig Nelson, who voiced the dad in The Incredibles, his sci-fi spoof about superheroes trying to lead suburban lives, "There are parts of Brad in every character. It's a committee he carries around in his imagination."

Although he made his first short at 14 and was at Cal Arts with John Lasseter and Tim Burton, he was too ahead of his time for Disney or other studios.

"I tried for years to get people to go for ideas that I had and ideas that I still believe in. I'd always get them excited. I'd always get enough money to start development but they'd never clear my planes for take-off until fairly recently."

His haunting breakthrough feature The Iron Giant, about a boy who befriends an innocent giant robot the government wants to destroy, was produced by Warner Bros just as they were closing down their animation division.

"It was like having free rein on the Titanic after the iceberg hit.

We all knew the ship was going under but until we did we could do anything we wanted to do."

John Lasseter, who lured Bird to Pixar in 2000 to make The Incredibles, said: "It was like having the most amazing racehorse strapped to a plough. We unhooked him from the plough and gave him a huge meadow to run in." Bird laughs when I remind him. "He gave me more than a meadow. He gave me miles and miles of nice green fields."