Now that the Royal Family has said farewell to Prince Philip, attention will turn to Queen Elizabeth II's 95th birthday on Wednesday and, in coming months, the celebrations marking her 70 years on the throne.
This combination of events is reminding the United Kingdom that the reign of the queen, the only monarch most of her subjects have ever known, is finite.
That has triggered speculation about how long she will remain on the throne, what the monarchy will look like in the future and, for some, even whether it should continue to exist.
“The queen is certainly moving now into the twilight of her reign and a new phase of her reign,'' said Anna Whitelock, director of the Centre for the Study of Modern Monarchy at Royal Holloway, University of London. “She now is a widow, and it remains to be seen how she's going to respond to that.''
While most observers say the queen is unlikely to abdicate given her lifelong commitment to public service, she has already started to turn over more responsibilities to Prince Charles, 72, her eldest son. That process is likely to accelerate following Philip's death.
Charles' increased role began gradually, when the queen began cutting back on long-haul flights, resulting in Charles taking her place at a 2013 Commonwealth Heads of Government meeting in Sri Lanka.
Then in 2017, he represented the queen at the annual Remembrance Day ceremony marking the end of World War I, laying the monarch's wreath at the foot of the Cenotaph in London. It was the first time the queen hadn't performed the solemn ritual, other than when she was pregnant or out of the country.
Since then, Charles has taken on an increasing number of public engagements and been named the queen's designated successor as head of the Commonwealth, a voluntary association of 54 nations with links to the British Empire.
“Symbolically, the transition towards the succession is already underway,” said Ed Owens, a historian and author of “The Family Firm, Monarchy, Mass Media and the British Public 1932-53.”
“I anticipate that we're going to see a lot more of Prince Charles in the next couple of years so that we, as a people, start to see him in his future role as king.”
For now, the longest-serving monarch in British history continues to reign. But she will do so without Philip, the man the queen called her “strength and stay,” a source of emotional support in her often lonely job.
Her loss was underscored by Saturday's funeral at St. George's Chapel on the grounds of Windsor Castle, where the figure of a widow in black sitting alone offered a glimpse of the next solitary phase of the queen's reign.
“Constitutionally, Prince Philip's death doesn't change anything. But, of course, at a time when the queen is approaching her 95th birthday, she's vulnerable and ageing,'' Whitelock said.
“Clearly, Prince Philip's death has begun this transition to the future and the beginning of the end of this phase of monarchy.”
Questions about the end of the queen's reign will also fuel the debate over the long-term future of the monarchy, seen by many as a symbol of national unity but by others as an obsolete vestige of the nation's feudal history.
The BBC received more than 100,000 complaints about its decision to pre-empt popular TV programs for round-the-clock coverage of Prince Philip's death, the most it has ever received about a single programming decision.
And while there is enormous respect for the queen, the same isn't necessarily true for Charles and other members of the royal family, said Graham Smith, chief executive of Republic, which campaigns to replace the monarchy with an elected head of state.
Philip's death “serves as a reminder to an awful lot of people, who on the whole don't think much about the monarchy from one day to the next, that change is coming,” Smith told the Express newspaper.
The queen's reign began with the death of her father, King George VI, on February 6, 1952. She was formally crowned on June 2, 1953.
During that ceremony, televised around the world, the queen promised to govern the United Kingdom and her other realms. Six years earlier, in a speech in South Africa, then-Princess Elizabeth made clear that her commitment was for life.
“I declare before you all that my whole life, whether it be long or short, shall be devoted to your service and the service of our great imperial family to which we all belong,” she said.
That is a pledge the queen intends to keep, said Robert Hardman, author of “Queen of the World,” which chronicles the monarch's influence and stature around the globe.
Even as she mourned last week, the queen attended a ceremony marking the retirement of her Lord Chamberlain, who organizes all ceremonial events for the palace, and continued to hold conversations with Commonwealth leaders.
That shows she has no intention of emulating Queen Victoria, who retreated from public life when her husband, Prince Albert, died unexpectedly at the age of 42, Hardman told the BBC.
“The signal she's been putting out during the last week is that this is going to be business as usual, that duty comes before self,” Hardman said. “She will continue with all her duties because … she took a coronation oath and she's sticking to it.”
But she won't be alone.