There will also be warships anchored on the Thames; attack helicopters on standby, and ground-to-air missiles ready to launch. All that, before you even get to the security on the ground. Such measures, however, may not only turn the capital into a city under siege, but simply prove to be ineffective.

Spectators may know for whom they are rooting at the Olympics, but they will not know who is watching them while they are at it. With the possibility of surveillance drones circling the skies of London and police using spy cameras that will leave no place unwatched, privacy campaigners fear it is the start of a slippery slope.

“I think it'll be an absolute tragedy for Britain if the largest part of the Olympics legacy was a surveillance legacy, where we install all this equipment in the name of national security and when the Olympics are over we keep using it,” Nick Pickles, director for Big Brother Watch told RT.

The spy in the sky has been piloted before in Britain by police forces, but it never took off again after one drone crashed into a river and the UK aviation authority denied granting the necessary licenses.

Those licenses are the only legal requirement before this sort of surveillance at the Olympics becomes reality. A minor hurdle for what is already Britain's biggest peacetime security operation, with the total cost topping $1.6 billion.

“It is worrying that the security bill has increased so drastically from initial estimates,” says Emma Boon of the Taxpayers' Alliance. “One of the reasons being given for this is the heightened risk of terrorism, which seemed incredible as an excuse at a time when the original estimates were made around the time of the London bombings, when London was considered to be a very high risk. It seems incredible they got the estimates so badly wrong in the first place and now taxpayers are facing an even bigger bill.”

The budget has ballooned by 100 per cent because initial estimates were woefully inadequate. However, that still could not stop two fake bombs being sneaked in under the radar at the stadium’s dummy runs. Not exactly great value for money.

London organizers have tried to play down fears London-2012 will be a city under siege, but with such a massive security operation, the traditional Olympic legacy of international friendship may not be the one that is actually left.