LONDON - For weeks, Sgt. Richard Brandon's prying eyes have been scanning the. On Friday, the route will be sealed off to the public with snipers on rooftops. But in the run-up to the prince's big day, CBS News correspondent Elizabeth Palmer reports Brandon's job is to zoom in and check out anything unusual, from workers and vehicles to tourist traffic.
"What we've been able to do is look into those difficult to search areas: roofs of buildings, canyons between buildings," Brandon said. "We're like an early warning system."
A system in place from the top down and the ground up.
On Friday, 5,000 police officers will be on duty - most of them unarmed.
"Policing an event like this is particularly difficult because the balance has to be struck between security and allowing the public to enjoy the event, which is what everybody - and especially the royal family - want the public to be able to do," said Peter Clarke, CBS royal wedding security correspondent.
But the terrorists are plotting. Police say the biggest threats of an attack come from radical Irish Republicans or al Qaeda. And there are the anarchists, who have vowed to make trouble and have been practicing. Last December, they surrounded, shouting, "Off with their heads!"
There's also a huge police effort dedicated to tracking unstable people, from lovesick stalkers to political zealots. Really anyone who would find the idea of disrupting the royal wedding irresistible - especially with 2 billion people watching worldwide.
The royal family has always been a magnet for the unhinged. There have been 8,000 incidents in just 20 years, including a stalker who pursued Princess Diana and a student who fired a starting pistol in front of Prince Charles. Even if they mean no harm, any strange behavior with police on high alert can turn ugly fast.
The vast royal wedding security operation, costing $30 million, is the most expensive in British history. It will be a success if, at the end of the day, it was barely noticed.