Police have increased their patrols at the MotoGP British Grand Prix at Silverstone this weekend as a result of the increased terror threat nationally - but have stressed there is no specific threat to the event.
A spokesman said there would be more officers and they would be more visible as they carried out checks both at the circuit and at campsites.
Visitors to the site were urged to be vigilant and report any suspicious activity as soon as possible.
Bosses at Silverstone racing circuit said they were disappointed to have lost the MotoGP British Grand Prix - but that extending their contract did not make financial sense.
The circuit said it had invested heavily to develop its site specifically to host both the Moto GP championships and Formula 1 and had helped to make the series a successful event.
But Richard Phillips, managing director of Silverstone Circuits Limited, said it could not come to an agreeing with the Dorna, the event's rights holders.
But the circuit has not rule out hosting the British Grand Prix next year while the event waits for the Circuit of Wales to be completed.
Silverstone has lost the contract to host the British Grand Prix of the MotoGP.
The event will take place at the Northamptonshire circuit next month.
But now a five-year deal has been signed to hold future meetings at the not-yet-built Circuit of Wales, which will be near Ebbw Vale in South Wales.
It will host its inaugural event in 2016 with MotoGP's official website suggesting next year's British Grand Prix could take place at yet another venue.
Since the beginning of the British motorcycle Grand Prix in 1977, only the courses at Donington and Silverstone have been used.
Silverstone has come to the end of its own five-year deal.
The Circuit of Wales could have its contract extended by a further five years if the deal proves to be a success, meaning Silverstone would have to wait until 2024 to bid again for the event.