Top button issue: Corbyn, Obama, Trudeau and the meaning of an open collar

The Labour leader has made the undone shirt neck his trademark look, but it's not just the politicians of the left cutting loose We find ourselves in an age of button diplomacy. Jeremy Corbyn, Justin Trudeau and Barack Obama - three very different politicians - are all fans of the unbuttoned top button. But what does the look tell us about their policies and their personalities? An undone button is Corbyn's sartorial trademark. Criticised for failing to properly tie his tie (thus, it's said, hin...