If the Police shut the High Street one day and my colleague asks me why, I may say to them :
They will probably have done that because of the accident this morning,
is this peculiar to BrE ?
'They will have done' is a future expression. But I am speaking of a past event. I could say 'they would have done that because ...' or 'they did that because ...' which both express past events.
But I often express 'will have' to denote something that is past.
Does AmE do this as well ?