LONDON — Sadiq Khan, the Labour Party’s mayor of London, romped to victory Saturday, securing a record third straight term at City Hall, on another hugely disappointing day for the U.K.’s governing Conservatives ahead of a looming general election. Khan won a little over a million votes, or nearly 44% of the vote, more than 11 percentage points ahead of his main challenger, the Conservative Party’s Susan Hall. His is the biggest individual mandate of any politician in the U.K. There had been... Read this story