A leaked Brexit document predicts a “catastrophic collapse” of the U.K.’s infrastructure if Britain leaves the EU with no deal. Above, British Prime Minister Boris Johnson gestures as he speaks outside 10 Downing Street in London in July.

A leaked Brexit document predicts a “catastrophic collapse” of the U.K.’s infrastructure if Britain leaves the EU with no deal. Above, British Prime Minister Boris Johnson gestures as he speaks outside 10 Downing Street in London in July.