The opening two free practice sessions of the British Grand Prix were affected by torrential rain, at the beginning of a weekend that could be characterised by wet weather during qualifying and the race as well, according to the latest forecasts.

As both Friday free practice sessions were wet, teams were allocated an extra set of intermediate tyres as per a new regulation introduced last year to encourage extra running. This brought their total allocation up to three sets of Cinturato Blue wets and five sets of Cinturato Green intermediates (one set of which will be returned tonight). The slick tyres nominated for the weekend are the P Zero Silver hard and P Zero Yellow soft.

The full wet tyres were mostly used today, which are capable of dispersing 60 litres of water per second at full speed. The afternoon free practice session started off in even wetter conditions than the morning session - but with more rain expected this weekend, this provided a useful opportunity for the drivers to get used to the wet lines at Silverstone and try out the upgrades that many teams have brought.

The fastest time in the morning was set by Lotus driver Romain Grosjean, who went quickest with a time of 1:56.552 on the Blue tyres - around 10 seconds off the pace of the equivalent free practice session last year.

Halfway through the second session, Ferrari's Fernando Alonso was the first driver to try the Cinturato Green intermediate, in a session that was red-flagged briefly after the Williams of Bruno Senna went off. McLaren driver Lewis Hamilton set the fastest time of the day at the very end of the session with a time of 1m56.345s on the Cinturato Blue, ahead of Sauber's Kamui Kobayashi, who also used just one set of wet tyres all day.

Paul Hembery: "With the British summer weather at its best, we could be facing our first full wet weekend from start to finish, without running the dry tyres at all! As tricky as the conditions are, it was important for the drivers to get a feel for them today in case this is how the situation will remain for the rest of the weekend. A few drivers tried the intermediate at the end of the second session in order to have some idea of crossover points, which are likely to be one of the keys to the strategy. Conditions like this often result in surprises, so we are almost certainly in for an unpredictable weekend but it's a pity for the fans who didn't get to see much running today. Together with the teams we can certainly look at some solutions to encourage more running under these circumstances in future, such as allocating more tyres, but everybody would have to agree to this as we're not in a position to make the tyre rules ourselves. We've seen some teams run many more laps than others today, with Sauber completing the most, so this could be an indication that we will see some quite different strategies on race day. And If we end up using the wet tyres in the race, one set of full wet tyres has a predicted life of around 60 laps."

Sets used overall:

Intermediate: 10
Wet: 30

Highest number of laps per compound:

Intermediate: 13
Wet: 33

Longest runs per compound:

Intermediate: 5
Wet: 15

Check out our Friday gallery, here.