In late April, Will Lewis arrived at the former Georgetown home of Katharine Graham. Graham was the most revered publisher in the Washington Post’s history, who steered the newspaper through Watergate and the Pentagon Papers. Lewis is the Post’s recently installed CEO and publisher, and a bit of a fish out of water — a British former Rupert Murdoch man running a newspaper built around values at odds with Fleet Street. He came to the R Street mansion for Tammy Haddad’s annual pre-White...