By Alan Baldwin

SILVERSTONE, England (Reuters) - Australian Mark Webber won a sunny British Grand Prix on Sunday for Red Bull to deny Fernando Alonso a second successive victory and slash the Ferrari driver's Formula One lead to 13 points.

Alonso, winner at Silverstone last year, had led from pole position but was powerless to prevent Webber powering past six laps from the end and then take the chequered flag with a three second lead.

The victory was the 35-year-old's second of the season, after Monaco, and left him with 116 points to Alonso's 129 after nine of 20 races.

"Another great day for us and a great day for me to win here again. It is fantastic," he said on the team radio before being interviewed on the podium by triple world champion Jackie Stewart.

Webber's Red Bull team mate and double world champion Sebastian Vettel was third on a dry track with the sun shining over the circuit after days of rain that had left the campsites waterlogged and approach roads clogged with traffic.

Brazilian Felipe Massa was fourth for Ferrari ahead of the Lotus pair of Kimi Raikkonen and Romain Grosjean.

Jenson Button's British Grand Prix jinx continued, before a predicted crowd of more than 125,000 people, with the McLaren driver failing to stand on the podium at his home race for the 13th year in a row.

The 2009 world champion, who has never finished higher than fourth at Silverstone, started 16th and ended up with only a point in 10th.

His team mate Lewis Hamilton, the 2008 champion whose win that year remains the last by a British driver at home, was eighth after losing out to Michael Schumcher's Mercedes in the closing laps.

Brazilian Bruno Senna was ninth for Williams.

Williams could have hoped for much more but their Venezuelan Pastor Maldonado collided with Mexican Sergio Perez on lap 12, ending the Sauber driver's race.

Stewards were due to rule on the incident but Perez said they had to act.

"This guy will never learn if they don't do something. He could hurt someone. Everybody has concerns about him," he told the BBC.

(Reporting by Alan Baldwin, editing by Keith Weir)