She is celebrated as part of a modern, enlightened approach to royal succession - a commoner without blue blood, a marriage of love rather than family constraint.
But Kate Middleton, the Duchess of Cambridge, may have far more patrician roots than once suspected.
Research undertaken by a Melbourne school teacher and his senior students has found that the Berkshire-bred wife of Prince William, second-in-line to the throne, is related to one of Britain's oldest and grandest families.
The 30-year-old is related to William Petty FitzMaurice, the 1st Marquess of Lansdowne, who was prime minister from 1782 to 1783.
The Marquess, whose ancestral home, Bowood House in Wiltshire, is one of Britain’s finest surviving stately homes, was instrumental in negotiating the end of the American War of Independence.
The ancestral connection is born from Catherine's second cousin three times removed, Lady Barbara Bullock. In 1917, Lady Bullock - nee Lupton - married a descendant of Petty FitzMaurice, Sir Christopher Bullock. Principal private secretary to Winston Churchill in 1919, Bullock went on to become permanent under-secretary at the British Air Ministry from 1931 to 1936.
Michael Reed, a history teacher at Hallam Senior College in Dandenong, told Fairfax Media that the discovery "grew out of a classroom activity based on celebrity family trees", and that students were asked to choose to study the ancestry of either 50 Cent, David Beckham or Kate Middleton.
"It was one thing to learn of Kate's British aristrocratic connections, but to now see the reaction and debate online is exciting."
While much has been made of the Duchess 'humble' roots - with links established from the Middletons to a street sweeper, coal miners and a prisoner - the new family connection tells a different story altogether.
William Bortrick, a royal genealogist and chairman of Burke’s Peerage, told the Telegraph: “Given what a fuss people have made about Catherine’s humble background, this will certainly make an interesting inclusion to the next edition of Burke’s Peerage, which we hope to publish after the birth of the Duke and Duchess’ first child.”
Reed, 47, sent his findings to the Duchess in October and received a letter of thanks from St James' Palace. At the time, Catherine would have been in the very early stages of pregnancy.
"It was kind of you to take the trouble to write as you did and thank you for bringing this to our attention," wrote Rebecca Deacon, her assistant private secretary.
"Her Royal Highness would have me send you her best wishes, and thanks for thinking of her in this way.”
Mr Reed told the London Telegraph: “It is a good feeling to know that I’ve unearthed something that may be of interest to the Duchess, her family and the Royal family.
“I could sense from the letter that she was pleased with my discovery, highlighting an aristocratic side of her family.”
Catherine has returned to official duties after a spell in hospital with acute morning sickness earlier this month, while a British nurse at the centre of an Australian radio prank call to the Duchess' hospital is reported to have blamed two 2Day FM DJs for her death.