The prejudice faced by London's first black policeman, how a new sign language emerged in 1980s Nicaragua, the Native American casino boom, plus the release of Nelson Mandela and China's much maligned 19th-century dowager empress.

Photo: London's first black policeman PC Norwell Roberts beginning his training with colleagues at Hendon Police College, London, 5th April 1967. (Hulton Archive/Getty Images)