The British Grand Prix weekend has begun in earnest, despite the current turmoil engulfing the sport. The threat of a breakaway series may be looming, but there is still a Formula One world title at stake. In front of his home crowd at Silverstone, Jenson Button is aiming to build on his 26-point lead at the top of the drivers' standings but it would seem Red Bull Racing are aiming to steal his thunder. Sebastian Vettel and Mark Webber were a comfortable one-two at the end of the opening practice session at the Northamptonshire track. Webber led the way until the dying moments with a lap of one minute 19.682 seconds, only to see team-mate Vettel knock him off top spot by 0.282secs. Meanwhile, Jenson Button has defended himself against accusations it is the car, and not his talent, helping him to F1 glory this season. The 29-year-old has had six wins from the opening seven races, catapulting him into a 26-point lead in the drivers' championship, a gap former British driver Nigel Mansell feels is unassailable. Mansell has described Button's Brawn GP car as "straight-out-of-the-box magical," in contrast to his Honda of the past two years that appropriately caught fire in what proved to be its final race in Brazil last October. So ahead of this weekend's British Grand Prix, many fans are asking: how much is it the car, and how much the driver? Button said: "When you are in a football team you don't say how much was the goalkeeper worth, how much was the defender, the striker. It's a team effort, and that's what Formula One is. "So it's the whole package, and when you've been with a car and a team for so long, you feel part of that team. You don't point at individuals."