The Crown has followed the Queen's reign through five series and the next one will depict the years after Diana's death in a Paris car accident on August 31, 1997.
Diana brought an unprecedented level of glamour, activism, and popularity to the royals, and is forever transfixed in the public mind as an icon in her prime at age 36.
Since her death, the family has had to navigate hurdles both personal and public, including controversies involving second sons Prince Andrew and Prince Harry. The social media environment, celebrity news churn, and changing public attitudes, have made it a vastly more challenging task.
The media activity of estranged royals the Duke and Duchess of Sussex is an ongoing stress test for the 1000-year-old institution.
Under a 2020 agreement in which Harry and Meghan became non-working royals, they are meant to carry on their own private lives in the US.
In reality, being royal is their point of difference among other socially conscious celebrities, and regular claims about their relatives keep their income ticking over. The pair, in the UK this week, have a Netflix deal, a podcast for her, and a memoir on the way for him.
The monarchy tends to deal with controversies by not directly commenting on claims and by trying to draw a line in public perceptions between the core group at the centre - the Queen, Prince Charles, and the Cambridges - and those further out.
Andrew lost his royal roles and use of his HRH title over his links to the Jeffrey Epstein scandal, which involved the Queen's son paying millions of pounds to a sex abuse accuser.
The royal strategy of the main official group getting on with inhabiting their roles, tends to get the monarchy through these storms.
But, 25 years after Diana's passing, the royal institution is inevitably heading towards major change with the Queen now 96 and in less robust health. She was due today to invite a new British leader to form a government at Balmoral in Scotland rather than at Buckingham Palace - a break with tradition.
There will be re-evaluations in various Commonwealth countries when Charles ascends the throne after his mother's long reign - perhaps in New Zealand but more likely in Australia, and especially in the Caribbean.
The Cambridges went on a tour of the Caribbean this year after Barbados decided to remove the Queen as head of state and the Duke said that: "Relationships evolve. Friendship endures."
William and Kate and their photogenic children are essentially being presented now as the long-term, dependable, future - in effect the eventual successor to the Queen as the most liked and respected royal.
It may not keep some countries in the fold but this institution tends to absorb and move on. The appeal Diana brought to it lives on in the official working royal family through her eldest son and grandchildren.