David Oyelowo, so brilliant in a recent theater production of Othello, playing the king against Daniel Craig’s Iago, is now a king again in Amma Asante’s A United Kingdom. Groomed to take the throne of Botswana, Seretse Khama is studying in London where he meets an office girl, Ruth Williams (the lovely, angelic Rosamund Pike). They fall in love. Let us just say, in this period drama based on a true story, the racism works both ways; and the colonialism is in-your-face exploitative. Some lines in this movie had the audience cheering: one wag, predicting the white woman would not last as the king’s wife in dusty Africa opines, “Wait till she finds out, there’s no Buckingham Palace in Botswana.” And when Ruth Williams is picked out of the typing pool, she asserts, “I’m no office girl.” Every time a British official condescends to the king, he offers a sherry, a double dig as in Botswana the blacks are not allowed to drink.