Ahead of today's opening session, the air temperature is 13 degrees C, while the track temperature is 18 degrees. It is cool, to put it mildly, overcast, but dry.

The lights go green and Kovalainen is first out, followed by d'Ambrosio, Perez, Alguersuari, Karthikeyan, Glock, Chandhok, Kobayashi and Ricciardo.

Hulkenberg is in for di Resta in this session, while Chandhok replaces Trulli for the entire weekend. At HRT Narain Karthikeyan is in Tonio Liuzzi's car.

Tyre compounds this weekend are medium and soft, the same as in Valencia, while, now that the diffuser row has blown over (sorry) the rules return to their pre-Silverstone status. However, changes to engine mapping between qualifying and the race remains a no-no.

In today's sessions, it's worth noting that the teams will also have access to a new soft compound which Pirelli is evaluating.

Within five minutes all but Webber and Button have been out for the obligatory installation lap. Moments later, the Australian and Englishman come out to play.

A number of teams are running updates here, Williams new rear wings on both cars and a new front wing on Barrichello's. The rear end of Heidfeld's car is covered in flo-vis paint, the German running a different (rear facing) exhaust in this session. Ferrari is running some minor aero updates, intending to run back-to-back tests in both sessions.

Seven years bad luck on the cards for Chandhok as his left mirror falls out of its casing.

Eighteen minutes into the session, Heidfeld post the first time of the weekend, the Renault driver crossing the line at 1:38.313. Next time around, 'Quick Nick' improves with a 37.987 as Perez posts 40.730.

As more and more drivers pour on to the track, Rosberg goes second, ahead of Perez, Alguersuari, Kobayashi, Barrichello and Ricciardo. Rosberg subsequently raises the bar with a 35.751.

A 33.576 sees Hamilton go quickest as Rosberg consolidates second and Schumacher goes third (36.203). Six Germans on the grid this weekend.

A big lock up for Barrichello at Turn 1, the Williams driver taking to the run-off. The track green and slippery this morning.

Hamilton ups the ante with a 32.996, the Englishman going quickest in all three sectors on the experimental soft tyres.

Thirty-five minutes into the session, Webber goes fourth with a 35.024 only to be demoted when teammate Vettel posts 34.739. Moments later the Australian improves to second with a 34.022 while Vettel loses time in traffic in S2 and fails to improve. All but d'Ambrosio, Karthikeyan and Glock have posted times.

As Schumacher locks up at Turn 11, Vettel goes quickest with a 32.760. Alonso pops up in fifth with a 34.099. Most drivers appear to be using the experimental softs.

At half-time, it's: Vettel, Hamilton, Webber, Alonso, Rosberg, Petrov, Button, Massa, Schumacher and Sutil. Still no time from d'Ambrosio. Thanks to the experimental tyres we appear to be getting a lot more running this morning.

Super slo-mo replay show Glock very lucky not to damage his car as his rides the kerbs at Turn 13 with a vengeance.

Alonso goes quickest in S1, the Spaniard on the experimental softs. He's quickest again in S3 however hit overall time of 32.574 is only good enough for second, 0.038s off Vettel's pace.

Make that 0.040s, as Vettel improves with a 32.534 having gone quickest in the first and final sectors.

Alonso goes quickest in all three sectors, crossing the line at 32.037 and thereby eclipsing Vettel by 0.497. The Ferrari maintaining the pace - and form - shown at Silverstone. Elsewhere, d'Ambrosio finally gets his name on the timesheets, the Belgian posting a 42.377.

Schumacher loses the rear end under braking for turn 1, as Webber and Massa look set to improve.