As previously reported, Jenson Button hosted a special press conference in London, late on Monday afternoon, and for the first time spoke of the events that have caused him to leave BAR for WilliamsF1 in 2005.

Previously, the Englishman had preferred to issue a terse "no comment" to questions about why his relationship with the team, which has taken him to third position in the drivers' championship, has soured, today he felt free to shed a little more light on the events that led to his decision to leave.

"There are many issues," he said, admitting that the team's failure to pay certain bonuses in one of them. "Contractually we had some differences," he continued, "we had some issues. That was at the end of 2003 and it hasn't been resolved.

"One of the reasons why I want to move on is because I am not 100% happy at the team," he added, "and one of the reasons I've not been happy is that there are issues with the contract. We've tried to resolve them but to no avail."

Although trying to be a diplomatic as possible, Button lays much of the blame for recent events at the door of team principal David Richards, a move which is sure to heighten speculation that British American Tobacco and Honda might seek a replacement for the Prodrive man.

Button claims that it was Richards who leaked the news of the WilliamsF1 deal to the media, saying that his manager John Byfield talked to the BAR team principal who immediately "leaked" the story to the press. He also claims that he wanted to talk to the assembled members of the team before they learned of his decision from the media.

Refuting claims that he is only moving to WilliamsF1 for financial reasons, Button revealed that he had been offered a "substantial incentive" to remain at Brackley.

"Money is not my aim in Formula One," he said. "My reason for moving to Williams is to be world champion. We had an agreement to be with BAR for two years, I honoured that agreement and I think I did a good job."

Talking of WilliamsF1, the team which brought him into F1 in 2000, he said: "I think that Williams in future is the team to be with. They've got the resources and Mark Webber and myself will be a great team. A Formula One driver's career has to keep moving. I can't keep finishing third or fourth in the championship.

"I don't think BAR is going to be the right place to be next year," he added, "because I don't think they will be able to challenge for the championship. The resources Williams have, compared to most F1 teams, is staggering."

Why Button has chosen today to reveal all, or at least some, is a mystery, however, his comments are hardly likely to go down well at Brackley.