Queen Elizabeth celebrates 70 years on the British throne in the coming week, with her platinum jubilee shining a spotlight on the uncertain future of not only the monarchy, but also the UK and the Commonwealth. The queen is now 96 and, sadly, her health has visibly declined in the past year since the death of her husband, Prince Philip, the Duke of Edinburgh. In this context, celebrations this week will remind audiences both in the UK and abroad of the unifying role she has played in recent decades. The queen is widely admired with her popularity fueled by visits to more than 130 countries during her long reign. Part of the reason this is so is that she represents a figure of significant continuity during a seven-decade period when the world has been transformed. In 1952, when Elizabeth succeeded her father, King George VI, and assumed the throne, Winston Churchill was UK prime minister, Joseph Stalin was leader of the Soviet Union, Harry Truman was US president, and Mao Zedong was the Chinese Communist leader. Then the Korean War was still underway, the People’s Republic of China was only two years old, and the UK was just about to join the US and Soviet Union as a nuclear power. The stability she has provided has been important for many institutions, including the monarchy and Commonwealth, but also the UK itself — for the continued union of England, Scotland, Wales and Northern Ireland could suffer from a potentially less popular UK head of state in the future. Starting with the Commonwealth, whose 54 nations account for around one-third of today’s global population, question marks hang over the body’s continued relevance. To be sure, the queen attaches high importance to the organization’s future, but uncertainty will only grow in times to come. Early “straws in the wind” are the fact that current Commonwealth nation Barbados last year became the latest state to remove the queen as its head of state. Similar sentiments are stirring in some other nations, too, including Australia, whose new Prime Minister Anthony Albanese is a long-standing republican who favors replacing his nation’s current constitutional monarchy. The winds of change are also blowing in the UK. While the queen remains a stabilizing force for many, the nation appears to be increasingly divided on geographic lines, especially given growing pressure post-Brexit for independence in Scotland. There are also signs of political change in Northern Ireland, with the nationalist Sinn Fein, which favors unification of the island of Ireland, becoming the largest single party in May’s elections. Beyond the debates about the Commonwealth and UK, there is also significant uncertainty over the future of the monarchy itself. Amid the high esteem in which the queen and some other royals are currently held, what is sometimes forgotten is that she has enjoyed bouts of significantly lower popularity. The 1990s were particularly troubled, with 1992 becoming her self-described “annus horribilis” when the marriages of three of her children, including her heir Charles, the prince of Wales, disintegrated, and Windsor Castle was almost destroyed by fire. Her response to the 1997 death of Charles’ first wife, Diana, was widely criticized at the time by the UK public. Nonetheless, the queen and her immediate family appear to have largely recovered from this period, and the media focus on the platinum jubilee is highlighting the continuing fascination much of the population has with the monarchy. This is a key driver of the fact that less than a quarter of British people today wants a republic, and many believe that it is better to have a nondivisive, nonpolitical head of state. That said, the personal popularity of Charles is neither as high as his mother’s nor that of his own son, William. Moreover, at 73, he is already at an age when many people are retired, and is the longest-waiting and oldest heir to the throne in UK history. Indeed, some polls show that a significant body of the UK public would prefer the monarchy to skip a generation from Elizabeth to William. This leaves open the significant possibility that the royal family could become less popular under Charles’ rule. In this uncertain landscape, the skill Charles eventually shows as Elizabeth’s successor could have implications not only for the monarchy, but also for the wider union of England, Scotland, Wales and Northern Ireland, as well as the Commonwealth. He will do well to learn the trick his mother has shown of being a reformer, while widely being seen as a force for stability, as the royal family continues to evolve to meet the changing contours of the 21st century.