The Duke and Duchess of Cambridge and their son, Prince George

Clarence House announced today that “Their Royal Highnesses The Duke and Duchess of Cambridge are very pleased to announce that The Duchess of Cambridge is expecting their second child. The Queen and members of both families are delighted with the news.” The announcement follows months of speculation concerning William and Catherine’s plans to expand their family. Various media outlets have already dubbed the forthcoming royal baby, “the spare” after Consuelo Vanderbuilt’s famous phrase “the heir and the spare,” coined to describe her two sons, born in her loveless first marriage to the 9th Duke of Marlborough.

Portrait Consuelo Vanderbuilt, Duchess of Marlborough with her husband and two sons, whom she dubbed, “the heir and the spare.”

The designation, “spare” suggests that a second royal child, or second son prior the current succession reforms, always exists in the shadow of his or her elder sibling, experiencing constant comparisons to “the heir.” For the past three generations, “the spare” has presented in the media as the fun loving sibling, a royal rebel eager to challenge the boundaries of court protocol. Before the present reign, however, there was a strong change “the spare” would become a sovereign and have as many responsibilities as “the heir.”

When photographs of Prince Harry playing strip billiards in Las Vegas were leaked to the press in 2012, his partying was compared to his elder brother William’s work as a Search and Rescue pilot in Wales. William performed rescues the same week as Harry’s Las Vegas trip, emphasizing the apparent contrast between a responsible, dutiful “heir” and a carefree, thoughtless, “spare.”

Harry’s public image initially improved when served a subsequent active tour of duty in Afghanistan but when he spoke frankly of the need to “take a life to save a life,” the press compared his outspokenness to William’s more guarded approach to the media. Harry will be thirty next week and continues to attract speculation regarding his future role in the royal family.  He has received praise for his successful charitable endeavors and overseas tours His past girlfriends, most notably Chelsy Davy and Cressida Bonas, have been the focus of intense media attention. With the arrival of William and Catherine’s second child, he will be fifth in line to the throne.

The Duke and Duchess of Cambridge and Prince Harry at The 2011 Sun Military Awards at Imperial War Museum in London. (Photo by Arthur Edwards – WPA Pool/Getty Images

Both the Queen’s second son, Prince Andrew, and her late younger sister, Princess Margaret were judged unfavorably by the public in comparison to their elder siblings. While Prince Charles and Princess Anne are praised for their charity work, their younger brother Andrew has been dubbed “Air Miles Andy” for his extensive travels during his time as a British trade envoy.  When Andrew was Harry’s age, he had a similar reputation to the current “spare.” Like Harry, Andrew was praised for his military service but his relationships attracted press attention, earning him another nickname, “Randy Andy.”

In 1952, Princess Margaret appeared carefree compared to her dutiful elder sister, the new Queen, but her status as “the spare” did not allow her freedom from the royal conventions of the time. In 1955, Margaret ended her relationship with the divorced Group Captain Peter Townsend, stating, “Mindful of the Church’s teachings that Christian marriage is indissoluble, and conscious of my duty to the Commonwealth, I have resolved to put these considerations before others.” Margaret married Antony Armstrong-Jones, a society photographer, in 1960, and became a divorceé herself in 1978. Revelations regarding Margaret’s extramarital affairs and spending attracted considerable negative attention and there were calls from UK Labour MPs for her to be removed from the Civil List.

King George VI, the most recent second son to become King

The experiences of Harry, Andrew and Margaret suggest that William and Catherine’s second child will face a lifetime of comparisons to older brother Prince George and a struggle to balance personal fulfillment with expected royal duties. This pattern, however, is a comparatively recent one. Prior to the present Queen’s reign, there was a strong chance that “the spare” would become the sovereign. Henry VIII, Elizabeth I, Charles I, Anne, George V and George VI were all second sons or second daughters who unexpectedly became Kings and Queens. (When the future George V became a direct heir in 1892, his “spare” was his sister Louise, Duchess of Fife, the most recent brother/sister “heir and spare.”) Royal “spares” with living elder siblings sometimes found opportunities to rule outside Britain. Queen Victoria’s second son, Prince Alfred, became Duke of Saxe-Coburg-Gotha. King John’s second son, Richard, was elected ruler of Germany “King of the Romans” in 1256. The life of “the spare” contained as much responsibility as the life of “the heir.”

The popular perception that the “spare” has fun while “the heir” performs extensive royal duties is a recent one, dating from the present reign. The 2012 Diamond Jubilee Thames river pageant emphasized the direct royal line – the Queen and the Duke of Edinburgh, the Prince of Wales and the Duchess of Cornwall, the Duke and Duchess of Cambridge and Prince Harry – rather than the extended royal family. In a streamlined royal family that precludes extensive engagements for royal cousins, William and Catherine’s second child may one day face a busy schedule of royal engagements with little time to act as the fun loving counterpart to a dutiful older sibling.