Concern over Buhari

* One of the world's most populous countries has been without its leader for almost a month, and no one seems willing to explain why. Muhammadu Buhari, the 74-year-old President of Nigeria, has been the subject of swirling rumours, conspiracy theories and downright fabrications since he flew to London on 19 January. Buhari's special adviser, Femi Adesina, said the President needed to stay in London to ‘complete and receive the results of a series of tests recommended by his doctors’.