Ahead of today's opening practice session, the air temperature is 18 degrees C, while the track temperature is 17 degrees. There has been rain for much of the night and sadly, for those camping the surrounding fields, it is still raining.

With much of the UK forecast to be hit by up to a month's rain in the next twenty-four hours, it is likely that Silverstone will receive its fair share. Indeed, organisers have already assured fans that contingency plans are in place should the conditions deteriorate. Anyone who knows the area - especially those who were here in 2000 - will be aware that when the weather deteriorates here it really deteriorates.

Most of the teams have brought updates here this weekend, but it is highly unlikely that we'll be seeing much of them, or the benefit they bring, today.

To further complicate matters, Pirelli is trying out a new harder compound here today, the Italian manufacturer eager to try it out before it is introduced next season. The main compounds this weekend are hard (prime) and soft (option).

Three teams are running test drivers this morning; Williams has Bottas standing in for Senna, HRT has Clos in for Karthikeyan and Bianchi is driving Hulkenberg's Force India.

The lights go green and surprisingly the drivers are keen to go out, if only to get the installation lap out of the way. All are on wets.

Perez is the first driver to post a time, the Mexican crossing the line at 2:11.663. All but the Force Indias - which much surely be used to the weather at this circuit - have been out.

"The forecast says that this is pretty much how its going to be," Kovalainen is told, "however, it could get worse." It probably will guys, it probably will.

Being a former airfield, Silverstone is flat, consequently standing water is a major issue here. Even on full wets the drivers complain of aquaplaning.

Twelve minutes into the session, Kobayashi is the only driver on track. In the pitlane McLaren carries out a number of pit stops.

Kobayashi posts a 2:04.479, the Sauber driver subsequently running into trouble at Club, the Japanese a passenger on what appears to be a mini lake.

As Pic posts the third time of the day (2:11.760), Vettel heads down the pitlane in the magnificently liveried Red Bull, the car sporting the images of thousands of fans who have donated to its Wings for Life charity. Webber on track also.

No sooner has Vettel posted a 2:10.702 than teammate Webber goes quickest with a 2:01.153. A 2:01.729 sees Ricciardo go second. The Australian, like his French teammate, needs a result this weekend.

Webber improves to 1:15.719 but Ricciardo is on a hot lap, going quickest in the first two sectors. The Toro Rosso driver crosses the line at 1:58.581.

As Ricciardo ups the ante with a 56.827, Vettel improves to third, ahead of Vergne, Kovalainen, Petrov, Kobayashi, Clos, de la Rosa and Perez.

As Ricciardo gets all out of shape, Clos has a big spin at Turn 5 (Aintree). Interestingly, the Spaniard is the first driver to actually spin this morning. Elsewhere, Grosjean goes second with a 57.058.

Grosjean subsequently improves to 1:56.552, as Massa goes fourth and Schumacher seventh. Still the rain falls. Indeed, as Kobayashi spins, the onboard camera on Hamilton's car reveals some very, very threatening clouds in the distance.

A big spin for de la Rosa at Turn 5, however, a far better recovery than his Spanish teammate.

As Button leaves his garage the rain is falling even heavier. Elsewhere, on his first timed lap, teammate Hamilton goes fourth (57.715).

A bib, big spin for Glock, his team still reeling following Maria de Villota's tragic crash earlier this week.

HRT reveals that de la Rosa reports that some sections of the track are now "dangerous". As if to prove the pint Rosberg runs wide and loses all control on the soaking grass.

At half-time, it's: Grosjean, Ricciardo, Hamilton, Perez, Massa, Webber, Kobayashi, Schumacher, Rosberg and Vergne. All but Alonso and the Force Indias have posted times.