Britain is watched by an estimated 5.9 million closed-circuit television cameras. CCTV can offer a unique insight into human nature at its best and - often - at its worst. But who are the people who keep watch of this footage around the clock? And how has CCTV technology advanced to help public authorities protect citizens on the streets? This series meets the surveillance operators who keep an eye on our public spaces and - in some cases - our private homes, and hears their frank insights into what they observe.