​Royal siblings: From Princes William and Harry to Princesses Beatrice and Eugenie

Prince George will soon have a little brother or sister to play with now that the Duchess of Cambridge, née Kate Middleton, is due to give birth. The baby's arrival will mark an exciting change for the 20-month-old royal, who stands to gain a lifelong friend with whom he can commiserate and share the spotlight.

There was a time when being born the "spare" was considered an unlucky hand in the line of succession, but Prince William and Prince Harry have changed all that, and George need look no further than his father and uncle to understand the importance of sibling love. Best friends from a young age, the princes grew up in the public eye together and have remained incredibly close since the loss of their mother, Princess Diana.

ROYAL SIBLINGS THROUGH THE AGES: CLICK ON THE IMAGE FOR THE GALLERYWilliam and Harry have been best friends from a young age

Diana and her siblings – brother Charles and sisters Sarah and Jane – were also born into an aristocratic family with royal ancestry, and they, too, remained steadfast friends until the Princess of Wales' death in 1997. Charles, a.k.a. the Earl of Spencer, was especially heartbroken over the loss of his beloved sister, delivering a stunning eulogy at her funeral that moved millions.

“Above all we give thanks for the life of a woman I am so proud to be able to call my sister, the unique, the complex, the extraordinary and irreplaceable Diana whose beauty, both internal and external, will never be extinguished from our minds,” he concluded, his eyes brimming with tears.

Of course, William and Harry are hardly the only two peas in a royal pod. The Duke of Cambridge's cousins – Princess Beatrice, 26, and Princess Eugenie, 25 – are practically inseparable, so much so that when Eugenie moved to New York City her older sister quickly followed suit. Eugenie has previously spoken about how close they are, saying:

"We get on fantastically well, perhaps because we do and think differently.

"Like all sisters, we have silly arguments about unimportant stuff, but we do love each other to death."

Princesses Beatrice and Eugenie are extremely close in age and bond

Even the older generation of royals forged intimate bonds with their siblings. Queen Elizabeth II and her late sister, Princess Margaret, were famously “very, very close," according to Margaret's biographer, Christopher Warwick. "There was always a loving bond between the two of them. She and Margaret spoke pretty much every day on the telephone."

Here, as we wait to welcome Prince George’s little brother or sister, we look back at some of the British royals’ most famous sibling relationships.

Queen Elizabeth II and the late Princess Margaret were royal peas in a pod

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