 Complete the following phrase:  Uncertainty over rule changes and exemptions concerning the use of off-throttle blown diffusers dominated off-track discussion at the British Grand Prix, though consensus within the media was that the issue did not directly affect the sport. Mark Webber started from pole position in the race; however, Sebastian Vettel took the lead on the first lap. A mistake from Red Bull Racing in the pits allowed Ferdo Alonso to take control of the race, which he went on to win by sixteen seconds, his first victory since the 