A carefully selected sample of households (4,500) are provided with elecronics which monitors which channel they are watching. Each member of the household presses a button to indicate when they are actually in front of the box. The Broadcaster's Audience Research Board collates this data, weights it for socio-demographic reasons and publishes it overnight to all broadcasters and advertisers.

Surely in the 21st century with the vast majority of households using set top boxes, they could provide a more exact representation of who is watching what? X amount of 4,500 people (considering 50+ million in the UK watch TV) isn't enough to determine that 15 million watch 'this' and only 10 million watch 'that

Yeah, I know, not enough people, but do I want some nosy person wanting to know what programmes I watch?