Rain drenched the Silverstone circuit at the British Grand Prix yesterday, severely restricting practice and leaving thousands of spectators stranded in traffic jams amid treacherous conditions.

Those who made it through the congestion watched local favourite Lewis Hamilton post the fastest time across two 90-minute sessions.

The McLaren driver, who is seeking his first win at Silverstone since the rain-soaked 2008 race, clocked 1 minute 56.345 seconds with conditions improving slightly in the afternoon.

Kamui Kobayashi of Sauber was 0.129 seconds adrift. Mercedes driver Michael Schumacher was next fastest, nearly two weeks after coming third at the European GP for his first podium finish since coming out of retirement two years ago.

Championship leader Fernando Alonso was one of three drivers who failed to set a time in the morning with spray hampering visibility. He was 10th fastest in the second session.

The rain-sodden track remained hazardous, with Bruno Senna spinning out of control in his Williams and crashing into a barrier, leading to the red flag being brought out for 10 minutes in the second session.

Alonso’s brakes struggled on the wet track, causing him to slide onto the grass and hit a barrier to lose his front wing.

The incidents appeared to vindicate the cautious approach adopted by the teams, but the reduced time on track denied the limited number of fans in attendance much of a spectacle.

Silverstone’s management described the conditions as a “nightmare” with an unexpectedly large demand for campsites at the circuit adding to the chaos caused by the deluge.

“This is the first year we’ve had such bad problems (for 10 years), which is largely down to all the fields giving out,” Silverstone communications head Katie Tyler said.

There was a tailback of five miles along the main road leading to Silverstone by Friday lunchtime. The situation could be exacerbated at the weekend with 100,000 people expected today and a sell-out of 125,000 on race day.

“If we get more rain, we have to be honest about it — it will be slow and there will be problems,” Tyler said. “We’ve loaded all the hard-standing car parks today, but we have used some of the other car parks that aren’t hard-standing. They may well be in a bad state tomorrow.”