When Elizabeth II arrives in America tomorrow to mark the 400th anniversary of the British settlement at Jamestown, she will appear more familiar, more accessible, and more understandable than ever before.

Thanks to Helen Mirren’s Oscar-winning portrayal in “The Queen,” the richest woman in the world, who has presided with wisdom over the British constitutional monarchy for nearly 56 years, seems to have been brought into sharp focus.

What Dame Mirren’s finely wrought caricature sought to expose is the human side of a woman who has hidden herself behind her august role since she inherited the crown from her father, George VI, when she was just 25. But it would be a mistake to imagine for a moment that “The Queen” has brought us closer to understanding Elizabeth II than, say, what Frank Langella’s brilliant portrayal of Richard Nixon in “Frost and Nixon” told us what Tricky Dick was really like. What we have witnessed is not great biography — it is great acting.

Good actors suspend our skepticism and make us believe we are witnessing the characters they are assuming. Playing Elizabeth in a movie as a reserved, willful, artful public idol and grandmother is credible and convincing, but it is not at all the same as coming to terms with the real woman who sits on the throne.

Elizabeth II herself remains a mystery, and deliberately so. To lose mystique would be to diminish the majesty and authority of the sovereign in whose name every act of the British state and Parliament is made.

Never a demonstrative person, the real queen has gone out of her way to protect her prime responsibility as a constitutional monarch: that, as the personification of the British state, she must remain aloof from day to day concerns. The maintenance of the monarchy and the safeguarding of her family’s birthright depend upon that eternal truth.

To that end, Elizabeth II has never granted a press interview. Even Barbara Walters has not managed to get from the world’s most sought-after celebrity the biggest “get” of them all. And, notwithstanding that her main activity is parading in public, the queen has always zealously protected her privacy.

Those who are about to meet the queen are briefed that they should speak only if spoken to and should not pass on anything she may say. Not that there is ever much worth quoting.

After being posed an obvious question, her replies are rarely more than, “Really?” or “What fun!” Newspapers who dare release private correspondence with members of the royal family are challenged in the courts. Those, like Princess Diana’s butler, who make their living out of exposing the secrets of the royal family, are shunned. Even American presidents who dare touch the queen, or put their arm around her, are reprimanded for having invaded her personal space.

For Americans, who like to become instantly familiar, such studied decorum can seem unnecessarily haughty, but that would be a misconception. To serve as a successful British monarch it is essential for the queen to remain above the fray. The selfish behavior of her ill-disciplined Uncle David, Edward VIII, who dared poke his nose into labor relations and put his personal interest before duty by insisting upon marrying a divorcee — fine for a commoner, but not for a monarch whose duties entail heading the Anglican church — remains a haunting example of how not to do the job. The grisly memories of Diana, out of love and way out of control, are another chilling reminder of what happens when protocol is abandoned in favor of populism.

So our knowledge of the woman who inhabits the role of queen remains deliberately dodgy. We know that she loves horses and riding — she enjoyed riding alongside Ronald Reagan. She also, like her mother, loves watching horse racing and owns race horses. She used to talk racing with Winston Churchill. She likes looking at her extraordinary collection of fine art, but not too often. (She is hardly an aesthete.) She sleeps in a separate bedroom from that of her husband. She takes interest in disappearing breeds of farm animals. She is never happier than padding around her Balmoral estate in her Wellington boots, with her pack of corgi dogs in tow.

Little of Elizabeth’s private life will be on show this week in Virginia. Nor will we see, when she visits the grieving campus of Virginia Tech, the profuse acts of public empathy shown by the electoral politicians who raced to the scene of the tragedy. The queen will seem concerned but cool, maternal yet strangely unmoved. Encountering a woman who eventually found a way to apply balm to a nation grieving over the loss of Diana, Princess of Wales, the students will discover that one of the queen’s most precious gifts is to know how to listen.