Still best known for casting Tilda Swinton as a sex-shifting 400-year-old nobleman in the 1992 movie of Virginia Woolf’s novel Orlando, the British writer-director Sally Potter tends toward earnest experimentalism. Who’d have thought she’d make a straightforward coming-of-age period drama? Ginger & Rosa doesn’t skimp on Potter’s open-hearted sincerity, but as a simple romanticized recollection of London in the early 1960s, it seems narratively unchallenging. The eponymous teenagers, born at the same time as the atomic bomb, find their friendship tested by a Cold War adolescence, with parent troubles mounting and life paths diverging into prayers and protests. Rosa is played by Jane Campion’s daughter, Alice Englert, who supplies a distinctly youthful art-house-lady cred, but the movie’s emotional power comes from a great and vigorous central performance by Elle Fanning as Ginger. After clashing with her ruefully domesticated mom (Christina Hendricks) and bohemian narcissist dad (Allesandro Nivola), she takes up with a supportive gay couple (Timothy Spall and Oliver Platt) and their American writer friend (Annette Bening), only to endure a falling-out with Rosa of approximate equal enormity to the Cuban Missile Crisis. Potter’s shabby-chic aesthetic seems sometimes more eloquent than her dialogue, but Fanning is as obviously an inspiration to Potter as she was to Sofia Coppola in Somewhere, and very much at home in this heady atmosphere of Brubeck and turtlenecks and pre-adult tribulations.