A.O. Scott is a film critic for the NYT.

In the endlessly popular musical “Billy Elliot,” the villain is played not by an actor but by a larger-than-life puppet with a gigantic head, an effigy of the kind that sometimes still appears at European protest rallies. This one has a beaked nose, a pronounced overbite and upswept blond hair, a visage immediately familiar to anyone who remembers the 1980s, and one that theatergoers — paying $100 a ticket for a dose of solidarity with the beleaguered British proletariat in the age of late capitalism — are eager to boo. “Who was that lady?” one of my children asked as we departed a recent matinee performance, not having recognized the Iron Lady.

Kids these days! How could they not know Margaret Thatcher? But then again, why would they? The common knowledge of one generation becomes esoterica in the next, to be dug out of history textbooks, Wikipedia or Dad’s overloaded brain. “Well, she was prime minister of Britain in the ’80s,” I began, and as I rambled through an impromptu lecture — watching their eyes glaze over as I botched the chronology of the Falklands War and triumphantly retrieved the names Arthur Scargill and Michael Heseltine from the memory hole — I was startled to discover how much I seemed to know about Mrs. Thatcher, and how much, in an odd way, she meant to me.

Her influence asserted itself when I was in my teens and left a permanent stamp on the person I would become. I should clarify that I am not British, and that my interest in the party politics of the United Kingdom is almost as meager as my enthusiasm for its royal weddings. And though I was a college student during part of Thatcher’s tenure at 10 Downing Street (including the years of the bitter coal-miners’ strike that is the backdrop of both the film and the stage versions of “Billy Elliot”), I was not one of those proud undergraduate conservatives with a picture of Ronald Reagan on the dorm-room wall, a marked-up copy of Friedrich von Hayek’s “Road to Serfdom” on the nightstand and a think-tank internship lined up after graduation....