Ahead of today's opening practice session, the air temperature is 14 degrees C, while the track temperature is 22 degrees. It is somewhat overcast but the sun is trying to break through. However, it is quite chilly.

As ever, when the lights go green, it is the Force Indias that lead the way, though they have plenty of company, with 15 cars on track within moments. Among the 'early risers' is Jenson Button, the hot favourite for victory this weekend.

While the majority of drivers return to their garages, having completed the obligatory installation lap, Heidfeld completes two laps before returning to the pits.

Just nine minutes into the session all twenty drivers have been out.

Several teams have updates this weekend, including Ferrari, however, the biggest noticeable change is the nose on the Red Bull which resembles what can only be described as being Platypus-like in appearance.

Sixteen minutes into the session, following a period of thumb-twiddling, Button breaks the deadlock, much to the delight of the partisan crowd. However, having completed another installation lap the Englishman returns to the pits.

As Buemi begins what looks likely to be the first flying lap of the day, Lewis Hamilton heads down the pitlane. The Frenchman crosses the line at 1:29.161, raising the benchmark to 27.212 next time around.

As Timo Glock posts 25.230, Buemi raises the bar ever higher with a 24.748. Elsewhere, Trulli tells his crew that the cool conditions mean that lap-times are well off the pace, however, he is hopeful that things will improve when it gets warmer. If it gets warmer. The Italian subsequently goes third quickest with a 25.771.

Thirty five minutes into the session, there are just three names on the timesheets, however, the Ferraris, Hamilton, Rosberg and Piquet are now on track.

Raikkonen's first lap sees the Finn go fourth with a 27.934, clearly struggling in the cool conditions. Next time round he posts 25.106, which sees him remain fourth.

Trulli goes quickest (22.890), as Raikkonen goes second, with Massa fifth ahead of Rosberg and Piquet. Replay shows Piquet having a bid spin at Copse, making full use of the run off.

Massa improves to third (23.742), before going quickest of all with a 22.469. Once again, Ferrari and McLaren are the only teams using KERS this weekend.

Raikkonen goes second (22.664), as Rosberg goes third, ahead of Trulli, Glock and Nakajima.

Massa, suffering with cold brakes, almost comes to grief as he trips up over a force India, as Rosberg and Nakajima make it a Williams 1-2.

A 21.726 sees Webber take the top spot ahead of Raikkonen, with all but Button now having posted times.

At half-time, it's: Rosberg, Webber, Raikkonen, Nakajima, Vettel, Alonso, Massa, Heidfeld, Kovalainen and Trulli.

Webber re-takes the top spot with a 20.865, taking it from his Red Bull teammate who had previously crossed the line at 21.119.

Sutil goes third with a 21.440, as Button, who has only completed 2 laps and has yet to post a time, leaves the pits. Next time around, Sutil improves to second.

As Barrichello improves to second, Button posts 24.132 to go nineteenth. Hamilton remains thirteenth as Trulli goes quickest with a 20.585.

A 21.427 sees Button go seventh, 0.842s off Trulli's pace, next time around the World Championship leader goes third with a 20.803.

With twenty-five minutes remaining, Button posts 20.487 to go quickest, as Webber goes quickest in the second sector. However, the Australian remains fourth.

Kubica, having completed just 8 laps, is rooted at the bottom of the timesheets, 3.893s off the pace, indeed, 1.9s off (nineteenth placed) Buemi's time.

Webber goes quickest with a 20.234, he subsequently goes quickest in all three sectors and raises the benchmark to 19.682. Teammate Vettel improves from third to second, closing the gap to 0.422s.

Glock has a big spin at Club, the German currently twelfth on the timesheets, 1.704s off the pace. Moments later, Bourdais gets well out of shape at Woodcote.

Alonso improves to fourth, as former teammate Hamilton improves to tenth. Their teammates remain sixteenth (Piquet) and nineteenth (Kovalainen).