"Most unfortunate that it should happen on Christmas day."
I'm wondering why 'should' is used in the sentence. Any difference from: Most unfortunate that it happened/happens on Christmas day.?
The modal verb should has quite a range of meanings all related in some way to the notion of obligation or necessity, among them that something was destined to happen.
P.S. Compare:
Why did this have to happen on Christmas day, of all days?