In a time of economic insecurity and an anti-establishment mood among so many voters here and elsewhere, the unexpected is no longer unthinkable. If Clinton’s problems and Sanders’s success are part of a surprising summer of politics here, the Corbyn victory was even more unthinkable only a few months ago after Labour suffered a historic defeat in the general election.

Here and in Britain, a political evolution continues. The election of Corbyn represents a dramatic break with the recent history of the Labour Party, a full and conspicuous rejection of the New Labour philosophy of Tony Blair, the former prime minister who won three successive elections but who now is a reviled figure for his role in prosecuting the war in Iraq in partnership with former president George W. Bush.

To American audiences, it is difficult to overstate the degree to which Blair is now an outcast in British politics. He may retain some affection here in the United States, but not in Britain. If there were any doubts about his current place in the politics of his country and particularly in the party he restored to prominence in the 1990s, it became clear with Corbyn’s landslide victory.