I'm not greedy, says Jenson

Button was asked if greed was a motivating factor behind him ditching BAR, with whom he has built a glowing reputation over the past two seasons, and he replied: "I'm definitely not greedy, although I am in one way because if I'm not world champion I'll be very upset. That is my aim in life. If I don't get that I won't be a happy bunny.

"It was a very tough decision initially, for many reasons, and it made it especially difficult knowing how it would look outside to the fans. It's nice to tell people the reasons for it and the ideas behind it."

Jenson shed some light on how the story broke in the media, and insisted that he was in contact with BAR chief David Richards, albeit through his manager John Byfield.

"I did tell David, the team principal, but through my manager," said Button. "Afterwards we were going to have a discussion. The problem was that there was so much leaked to the press, it made the situation very difficult. It would have been much easier to have the discussion in the background, away from the media, but didn't happen like that. That wasn't my plan, I wanted to keep it quiet so I could get back to the factory and tell the team and talk it through with them. That wasn't possible."

Button said he hoped that his relationship with Richards would continue to be amicable, although he was well aware it might have sustained irreparable damage: "We get on very well, our working relationship is very good, as it should be. I suppose we have been friends away from the circuit, and I'm not sure if that can be the same. I hope it is, we'll have to wait and see."

Despite the furore over his move, Button says there has been no problem with BAR team members during the Hungaroring race weekend, but seemed eager to join forces with Williams next season.

"I expected it to be more difficult this weekend," he said. "Even without hearing my side of the story, they have been very positive. A lot of people have been supportive. We've had a good season, I can't take anything away from the team.

"For me, though, Williams is a team for the future. They have a lot of experience and resources. I have to keep improving every year. Since 2001, every year has been a step forward. I need that to keep going really. Next year I want to be challenging for the world championship. Williams is the team I'm gonna do it with and Williams is the team that will give me that possibility."