Tost: Button never an option for STR

Button faced an uncertain future when Honda pulled out of Formula One at the start of December, and at the time Toro Rosso were the only team with a vacant seat.

But despite speculation linking Button with STR, the Briton stayed loyal to Honda until the team was rescued by Ross Brawn, while Toro Rosso ultimately confirmed Bourdais alongside Sebastian Buemi - which Tost said had always been the most likely scenario.

"To be honest, Jenson was never a choice for us," he said at the launch of the Toro Rosso STR4 today.

"Bourdais was always first on our list, and the contract was signed in January. The season starts in March, but as far as I know Jenson Button has an agreement with Honda and therefore there was never any negotiations with Jenson Button or his management."

Although Bourdais and Buemi took part in a shoot-out test with Takuma Sato during the winter, Tost said Bourdais had always been in line for the seat and played down the late announcement of his deal.

"I don't think it took so long," Tost said. "The season starts late. I myself was convinced that it would be Bourdais and therefore there was no hurry to sign the contract early.

"It was - let me say an agreement between us that he would drive for us, and then the contract is a formal thing which was signed at the end of January."