Paul Watters, head of roads policy at the AA, has told the Sunday Telegraph that "most accidents" on the road happen in the dark.
We do know that most accidents happen in the dark. It's also comforting for people, especially if they arrive back from somewhere in the night, when they have got a late train.
There are also suggestions that it increases crime. So it may save money in terms of energy but then you have to look at the cost in terms of security, safety and accidents, it may actually be more.