Boris Johnson begins Iran talks over Nazanin Zaghari-Ratcliffe

Imprisonment of British-Iranian mother is crucial issue facing foreign secretary as he meets counterpart in TehranBoris Johnson made a “frank and constructive” start to his sensitive first trip to Tehran, where he will meet President Hassan Rouhani as he lobbies for the release of a jailed British-Iranian.The foreign secretary’s visit comes as concerns grow about US president Donald Trump’s hostility to the landmark nuclear deal with Tehran, and deepening regional tension