Lance Corporal Alex Walton (L) and Corporal Dan Best of the RAF Regiment take part in a media facility at RAF Northolt in west London on July 13, 2012 to show off some of the aircraft and equipment that will be used to protect the London during the upcoming Olympic Games. A series of airspace restrictions around London and south-east England are set to be enforced from midnight.

Lance Corporal Alex Walton (L) and Corporal Dan Best of the RAF Regiment take part in a media facility at RAF Northolt in west London on July 13, 2012 to show off some of the aircraft and equipment that will be used to protect the London during the upcoming Olympic Games. A series of airspace restrictions around London and south-east England are set to be enforced from midnight.

Lance Corporal Alex Walton (L) and Corporal Dan Best of the RAF Regiment take part in a media facility at RAF Northolt in west London on July 13, 2012 to show off some of the aircraft and equipment that will be used to protect the London during the upcoming Olympic Games. A series of airspace restrictions around London and south-east England are set to be enforced from midnight.

Snipers with the Royal Air Force Regiment, look through the scopes of their sniper rifles as the military prepares for duty to provide security aboard helicopters high above the London Olympic games, at RAF Northolt, in London, Friday July 13, 2012. Aircraft that fail to comply with procedures within a restricted airspace zone around the Olympic venues could be subject to "lethal force" from the military, it is revealed Friday. RAF Typhoon fast jets and RAF Puma helicopters with snipers armed with hi-tech rifles will be among the military aircraft patrolling the restricted zone which comes into force during the London 2012 Olympic Games.

Lance Corporal Alex Walton (L) and Corporal Dan Best of the RAF Regiment take part in a media facility at RAF Northolt in west London on July 13, 2012 to show off some of the aircraft and equipment that will be used to protect the London during the upcoming Olympic Games. A series of airspace restrictions around London and south-east England are set to be enforced from midnight.

Lance Corporal Alex Walton (L) and Corporal Dan Best of the RAF Regiment take part in a media facility at RAF Northolt in west London on July 13, 2012 to show off some of the aircraft and equipment that will be used to protect the London during the upcoming Olympic Games. A series of airspace restrictions around London and south-east England are set to be enforced from midnight.

Lance Corporal Alex Walton (L) and Corporal Dan Best of the RAF Regiment take part in a media facility at RAF Northolt in west London on July 13, 2012 to show off some of the aircraft and equipment that will be used to protect the London during the upcoming Olympic Games. A series of airspace restrictions around London and south-east England are set to be enforced from midnight.

A sniper with the Royal Air Force Regiment, looks through the scope of his sniper rifle as the military prepares for duty to provide security aboard helicopters high above the London Olympic games, at RAF Northolt, in London, Friday July 13, 2012. Aircraft that fail to comply with procedures within a restricted airspace zone around the Olympic venues could be subject to "lethal force" from the military, it is revealed Friday. RAF Typhoon fast jets and RAF Puma helicopters with snipers armed with hi-tech rifles will be among the military aircraft patrolling the restricted zone which comes into force during the London 2012 Olympic Games.

Corporal Dan Best of the RAF Regiment takes part in a media facility at RAF Northolt in west London on July 13, 2012 to show off some of the aircraft and equipment that will be used to protect the London during the upcoming Olympic Games. A series of airspace restrictions around London and south-east England are set to be enforced from midnight.

Corporal Dan Best of the RAF Regiment takes part in a media facility at RAF Northolt in west London on July 13, 2012 to show off some of the aircraft and equipment that will be used to protect the London during the upcoming Olympic Games. A series of airspace restrictions around London and south-east England are set to be enforced from midnight.

Lance Corporal Alex Walton (L) and Corporal Dan Best of the RAF Regiment take part in a media facility at RAF Northolt in west London on July 13, 2012 to show off some of the aircraft and equipment that will be used to protect the London during the upcoming Olympic Games. A series of airspace restrictions around London and south-east England are set to be enforced from midnight.

An aerial view of the Fred Wigg building in east London where the British military are installing a missile battery on top of it as part of the defenses for the London 2012 Olympic summer games Friday, July, 13, 2012.

An aerial view of the Fred Wigg building in east London where the British military are installing a missile battery on top of it as part of the defenses for the London 2012 Olympic summer games Friday, July, 13, 2012.

An aerial view of a British military missile battery placed on top of the Fred Wigg building in east London part of the defenses for the London 2012 Olympic summer games Friday, July, 13, 2012.

An aerial view of a British military missile battery next to a reservoir on the Lea Valley in east London, part of the defenses for the London 2012 Olympic summer games Friday, July 13, 2012.

An aerial view of a British military missile battery next to a reservoir on the Lea Valley in east London, part of the defenses for the London 2012 Olympic summer games Friday, July 13, 2012.

An aerial view of a British military missile battery next to a reservoir on the Lea Valley in east London, part of the defenses for the London 2012 Olympic summer games Friday, July 13, 2012.

An aerial view of a British military missile battery on Blackheath common in south London, which is part of the defences for the London 2012 Olympic summer games Friday, July, 13, 2012.

An aerial view of a British military missile battery on Blackheath common in south London, which is part of the defences for the London 2012 Olympic summer games Friday, July, 13, 2012.

An aerial view of a British military missile position on top of the Lexington Building in east London, part of the defenses for the London 2012 Olympic summer games Friday, July 13, 2012.

Soldiers guard an exit from the Olympic Park on July 13, 2012 in London, England. An extra 3500 soldiers are to be deployed to guard the London 2012 Olympic Games after private security contactor G4S failed to recruit enough personnel.

Soldiers walk from the Olympic Park on July 13, 2012 in London, England. An extra 3500 soldiers are to be deployed to guard the London 2012 Olympic Games after private security contactor G4S failed to recruit enough personnel.