Jeppy

And voters can't make a decision in the dark?

Of course they can. But it is acts as a deterrent to vote and is much harder for campaigners and canvassers.

Recent phenomenon? How many winter elections have there been in the last century?

I count 8 since 1900 taking place in the winter months of December, January and February.

Oh and that drops to 5 if you take winter strictly being 21st December to 21st March. This of course is all by the by the question shouldn't be when but why. If it's to resolve Brexit then the correct mechanism is a 2nd referendum a GE can come later.