The toppling by anti-racism protesters of a statue of a slave trader in the English port city of Bristol has given new urgency to a debate about how Britain should confront some of the darkest chapters of its history. The statue of Edward Colston, who made a fortune in the 17th century from trading in West African slaves, was torn down and thrown into Bristol harbour on Sunday by a group of demonstrators taking part in a worldwide wave of protests. Statues of figures from Britain’s imperialist past have in recent years become the subject of controversies between those who argue that such monuments merely reflect history and those who say they glorify racism.