It's a role that calls for confidence and sure footing.
In just days, the most anticipated social event in decades is set to unfold with all the pomp and panoply that only the British can muster.
Catherine Middleton is about to become the wife of the man who, barring unforeseen tragedy, will one day become King William V.
As soon as the couple is pronounced man and wife in historic Westminster Abbey, Kate, as the wife of the second-in-line to the throne, will rank in order of precedence not far behind Queen Elizabeth II.
And yet beyond the history, pomp and circumstance, like any newly married bride, Kate will have joined herself to a new family.
But it is no ordinary family. To understand what kind of life she will embark upon, Kate need not look further than what William's great-grandfather, King George VI, had to say about himself, his wife and his two daughters: "We are not a family, we are a firm."
George VI, who reigned from 1936 to 1952, has gained new fame thanks to the highly acclaimed movie "The King's Speech."
His astute observation about the British royal family being "a firm" says much about the king's sense of duty and obligation, and highlights the expectations and pressures that will bear upon the newest member of the House of Windsor.
The shoes Kate will have to fill as a royal are huge. Far from being a mere adornment to the royal family, Kate must also be wife and mother of future monarchs.
It will be daunting, for these roles will be played out for all the world to see. A stellar example to emulate would be that most successful of modern consorts, the Queen Mother.
She buoyed her husband, George VI, throughout their marriage, particularly during World War II. She calmed his difficult temper, raised his confidence and helped him cope with his debilitating stammer.
Such was her ability to steel the resolve of the British in their fight against the Nazis that Adolf Hitler once referred to her as the most dangerous woman in Europe. The Queen Mother also rarely put a foot wrong in public. She glided with ease through five decades as the much-loved "Queen Mum."
Indications are that Catherine Middleton's popularity will mirror the Queen Mum's. Kate's recent public appearances were unrivaled successes. Crowds took to her, and Kate took to them.
She showed warmth, spontaneity and confidence, a polished style and charm that makes it look as if Catherine Middleton was to the manor born.
Such is not the case however. Far from being a blue-blooded aristocrat, Kate, on her maternal side, hails from decidedly working-class stock that includes coal miners.
More recently, Kate's mother, Carole, worked as a flight attendant. Carole and her husband, Michael, went on to build a successful family business selling inexpensive (and some might say, kitschy) party supplies on the Internet. Snickering snobs have whispered loudly that the family and, by implication, Kate, are simply nothing short of being arrivistes.
The Middletons need not heed all the carping about their daughter's supposed lack of credentials to join "the firm." Kate has shown that she has what it takes to succeed as a member of the House of Windsor.
When she and William split briefly in 2007, Kate could have spilled the beans on their relationship for a hefty fee. Instead, she kept a dignified silence.
Discretion served her well. A few months later, Kate was back with her prince.
There were also snarky comments from the media about "Waitey Katie," who seemed to be focused solely on becoming William's wife. But again, she kept her cool amid the harping.
And now she is just days away from becoming HRH.
Julia P. Gelardi, of Plymouth, is the author of "Born to Rule: Five Reigning Consorts, Granddaughters of Queen Victoria" and "In Triumph's Wake: Royal Mothers, Tragic Daughters, and the Price They Paid for Glory." Her latest book is "From Splendor to Revolution: The Romanov Women, 1847-1928."
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