14:40 Johnson has become UK's new prime minister after the Queen invited him to form a government in her name. Boris Johnson won the Conservative leadership contest in the summer of 2019. He was mayor of London (2008–16) and foreign secretary under Theresa May (2016–18). … At birth, Boris was granted both American and British citizenship. Boris Johnson, British Conservative Party politician who became prime minister of the United Kingdom in July 2019. Prime Minister Theresa May sits with then-Foreign Secretary Boris Johnson during the first cabinet meeting of May’s new team at 10 Downing Street in London on June 12, 2017. Boris Johnson was born Alexander Boris de Pfeffel Johnson on 19 June 1964, in New York City, USA, to Stanley Johnson and Charlotte Johnson Wahl, as the eldest of four children. He trounced rival Jeremy Hunt in the vote among 160,000 party members. The new premier will now head to Downing Street and make a speech. He led the successful ‘Leave’ campaign in the 2016 referendum on whether the U.K. should remain in the EU. New UK Conservative Party leader and incoming Prime Minister Boris Johnson arrives at the Conservative Party headquarters in central London on July 23, 2019. Johnson defeated Hunt …