Jenson Button has extended his management deal with Essentially Sport for another three years, but the Briton will no longer be managed by John Byfield, who is stepping down from his position as chairman and CEO of the management company.
Button has been managed by Byfield's Essentially Sport since 2002, after parting ways with his former manager, David Robertson.
The 24-year-old announced in August he would join Williams in 2005, following advice from Byfield, a lawyer by profession, that he was free to leave BAR. But the Honda-powered squad were able to keep the driver after successfully challenging the move with the sport's Contract Recognition Board.
"CEO and Chairman of Essentially Group, John Byfield, announces that he will be stepping down from the Board with effect from 1 January 2005," said the company in a statement.
"Having helped the Group to achieve its initial goals, he leaves the business well positioned for future growth and development. Mr Byfield will remain with the Company using his in-depth knowledge and skills to focus upon its motor sport interests."
The company said it will announce his successor shortly. Duncan Hickman, currently a non-executive director, will act as interim CEO in the meantime.