I'm not suggesting balmy evening light: it is just depressing when it gets dark at 4 o'clock. I'd rather have some "extra" time then rather than first thing in the morning. And there is something nice about a winter walk - you just dress up for it!
If we take ds to breaksfast club in the morning (at 8.15), it is already murky - so if we were on GMT+1, it would just be a bit darker.
It also means when he is older, and walking home himslef, then it will be lighter - which is apparently the key time for the accidents, when people are tired after a day at the office.
The headmaster of my primary school was horrified that they supported the expiriment - even then, they agreed with the argument that it would save lives.