Editor's note: Tom Rogan is a conservative writer for TheWeek.com and The Guardian. Although he's American, he grew up in London, England.
(CNN) -- The Windsors, ruling House of the British royal family, have endured world wars, personal tragedies and highly public scandals. In the 20th century, through moments of pain and joy, they provided the British people with a fixture of redoubtable comfort, an unchanging physical constitution in a world fraught with uncertainty.
But how will the British royals face their greatest challenge -- maintaining relevance in the 21st century?
The new prince born to Catherine, Duchess of Cambridge, and her husband, Prince William, will be a critical part of the answer.
It may be true that the royal family remains ingrained at the heart of the British establishment. The title ER (Elizabeth Regina) adorns the helmets of British police officers, the laws of Parliament still require royal assent and the monarch remains technical head of the UK armed forces.
But things change.
Next February, Queen Elizabeth II will have worn the crown for 62 years. She's 86 and her public appearances are becoming less frequent. Elizabeth's reign will one day end. And without the princess who won hearts in war and then became a queen in peace, the royals will have to re-win the public's affection. And they'll have to do so by navigating a changing British society; one more socially liberal and less predisposed to tradition.
Recent history suggests it won't be easy.
Consider the queen's experience following Princess Diana's death in 1997. Facing intense pressure to show personal emotion in the face of a loss that was felt widely, the queen hesitated. Public expectations conflicted with her conception of royal purpose, that of a stoic, unmovable figurehead. Her inclination was to mourn in private, allowing the politicians to provide the public face of suffering. Eventually though, realizing that times had changed, the Queen of England bent to the will of her people.
She recognized the intrinsic truth of her throne, one that the future king, William, and his son (the future king) will also have to grasp: that their royal adornments of power exist subject to the grant of their British subjects.
Ultimately, in an era increasingly defined by vigorous social entrepreneurship, institutional relevance is determined less by history, than by a perception of worth. It's in this sense that change, the ability of the royals to evolve and find sustaining worth, will determine whether they rise or fall.
So far, it seems that William gets this. When, on their wedding day, the future king and his wife drove down The Mall in an open-topped Aston Martin, the watching throngs reacted with elation.
Why such glee?
Because the crowds perceived a royal interpretation of cool Britannia; both seemingly natural and delicately informal. A simple act hinting at the prospect of a modern monarchy. Representatives to be proud of.
This success is crucial. Where royals are regarded as living in an overly insulated bubble, major problems arise. Just look at the outrage that has followed the recent outing of Prince Charles' (next in line to the throne) tax planning.
For royalists then, it's fortunate that the just-born prince defines royal change. He offers a royal family that is both necessarily distant and semi-relatable, an incarnation of royal tradition gelled to social modernity. In short, a prince for the present and a king for the future. But just as he'll live without worldly want, the prince won't be afforded a normal life.
As his parents and uncle have repeatedly found out, the media has little interest in royal privacy, especially for a royal destined to one day become monarch. Just as the spotlights of the world fixed on his birth, so too will they follow him in life.
That's the price of modern royalty.
And British history has begun its latest chapter.
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The opinions expressed in this commentary are solely those of Tom Rogan.