Why Do Cyclists Ride in the Middle of the Road?

In the midst of what seems to be a spate of cyclists-killed-by-car news comes this well-reasoned article from a motoring site in the UK.

http://www.motoring.co.uk/car-news/cyclists-why-do-they-ride-in-the-middle-of-the-road-_62617http://www.motoring.co.uk/car-news/cyclists-why-do-they-ride-in-the-middle-of-the-road-_62617