With the London Games just days from its opening ceremony, and the private security firm only providing half the guards it promised, another 1200 army personnel have been deployed.

The world is on edge, but key security advisers on the ground say despite the problems, London is ready to deal with any potential threat.

In the biggest peacetime security operation London has ever seen, an security umbrella has enveloped the city.

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No one knows more about terrorism and security in London than Peter Clarke - the former head of counter terrorism at Scotland Yard.

When terrorists struck London’s underground seven-years-ago he was the face of the investigation.

“That leaves an indelible mark on anyone involved in that. It really does bring to stark reality the vulnerabilities of an open transport system. That’s what we have and that’s why intelligence and preventative work is so important,” Clarke said.

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So what are the weak points in London’s security?

“There’s an inherent weakness in having a free and open city. That’s the paradox with these sorts of security operations. You can never completely control access to public transport, public spaces,” Clarke explained.

Security central is at the Special Operations Room where 12,000 camera feeds stream in live, 24 hours a day.

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“That gives them a huge amount of knowledge and understanding of what’s happening out there on the ground,” Clarke said.

“Overall there are thousands (of CCTVs) around the sites, but the trick is not to sit there looking at the screen thinking you’re going to understand what’s happening, but to use the information intelligently and analyse and piece it together with all the other information available to you.”

London has an entrenched and tragic history of terrorism dating back decades with the IRA, but never have security chiefs employed the sort of fire power they’re now using - including six surface to air missiles in a ring around the city, with the power of taking down a Boeing 747 full of passengers.

It’s a terrible thought, but one security chiefs must plan for.

“As part of sensible planning you plan for all eventualities, and that’s clearly an eventuality that has been taken into account in the planning. Heaven forbid anything like that should happen that would require that sort of capability and it hadn’t been put in place, then what would people say,” Clarke said.

In the weeks leading up to the Olympics five people posing a very real threat have been arrested and charged with terrorism offences. They’ll appear in court this week.

Security consultant and former Scotland Yard Royalty Protection officer Ken Wharfe believes securing the Olympics is made much easier today with state of the art technology.

“We have number plate recognition checks of individuals and cars that are instantly relayed back into the command station, that can be dealt with in a way that we could never do,” he said.

“If we have a suspect for example of a foreign race, we can now speak to an international control unit and find out that information immediately, whereas before the person would have to be detained and we would have to wait four or five days.”

As Princess Dianna’s former personal bodyguard Wharfe also points out security for the Royal Family will be tightened during the Olympics, but predicts the young royals in particular will definitely attend some high profile final events.

“They will have their own protections. Of course it will be supported by the military and additional police forces throughout the entire United Kingdom,” he said.

Already the UK Government has faced a debacle with the Olympic contracted private security firm unable to provide their full commitment of staff, and a further 3500 soldiers have hurriedly been deployed.

This week, just days before the opening ceremony, the Government has called up a further 1200 soldiers in.

Adrian Dhage was head of security at the 2000 Sydney Olympics and says he believes the most dangerous attackers won’t be middle eastern terrorists.

“Perhaps the most dangerous terrorists are the ones that appear from nowhere - the Timothy Mcveighs, or the guy that attacked us in Port Arthur. They’re the ones that don’t show up on intelligence networks, so they will be looking right across the spectrum,” he said.

Dhage has left the industry now and is using his expertise to write fiction instead and his latest novel is The Inca Prophecy.

With his infinite knowledge of security, he has these words of comfort: “they will be doing their best to lock London down. If I were going I’d be quite confident in the security they have in place.”

Clarke’s message for the Games is clear. “If anybody is going to try and do something to disrupt these Games, they’re not an easy target, and the chances of success have been diminished amazingly by the size of the security operation. It is a big operation. You will be captured you will be stopped.”

This reporter is on Twitter at @LauraSparkes7