Why do we have daylight savings time?
IMHO it would make more sense to ask why we have GMT - I think BST is much better, and I hate it when winter is confirmed by making the afternoons unnecessarily dark and gloomy, as if there is not enough of that already.
The reason I have heard for GMT is that if you advance the clocks during the winter, then schoolkids in Scotland go to school in the dark and get killed by motor accidents. But presumably with things as they are (GMT in the winter) they get killed on the way home instead. Either way, what the Scots do should be something for them alone - why burden the rest of us with their problems ?
It's original purpose was to save an hour of daylight, thereby reducing energy consumption and giving an extra hour for the benefit of many businesses that rely on daylight hours.
However, it has proven to be counter-productive in recent years.