LONDON, England - Silverstone circuit bosses want to see Formula 1 champion Lewis Hamilton pushed harder by his rivals in time for July's 2015 British Grand Prix.Hamilton's success so far in 2015, on the back of clinching his second title with Mercedes in 2014, has helped sell tickets for his home race but there could be too much of a good thing. The track's new MD, Patrick Allen, said at a media briefing: "My only concern is that if he wins everything by a country mile between now and July, if it becomes a procession, it damages the sport."It would be great if Sebastian Vettel could stir things up a bit." LOSE SOME FANSHamilton has won three of the four races so far in 2015 with four-times champion Vettel taking the other victory in Malaysia - only his second race for Ferrari since moving from Red Bull. Hamilton, who has started every 2015 GP from pole, won 11 of 2014's races - one of them Silverstone.Allen said Silverstone was 26% up on last year's ticket sales but feared the sport might lose some fans with the current state of racing.Mercedes, Red Bull and Ferrari are the only teams to have won races since 2013; Mercedes won 16 of 2015's 19 in 2014.Allen again: "We mustn't lose sight of what the fans come here for.. their heroes in a gladiatorial sense, not a guy on a data screen. When it gets to that, we've lost the very soul of the sport."Stay with Wheels24 for the 2015 Formula 1 season.