Britain's Prince Harry poses with his fiancee, actress Meghan Markle, at Kensington Palace in London on Friday. (Facundo Arrizabalaga/Epa-Efe/Rex/Shutterstock)
Associate opinions editor

Autumn Brewington, a journalist in Washington, is a former op-ed page editor and royal blogger for The Post.

Prince Harry and Meghan Markle’s engagement is more than a palace love story to cheer in a season of cheerless news. The happy union of a playboy-prince-turned-soldier-and-humanitarian and a biracial, divorced American actress-and-humanitarian — welcomed by Britain’s power structure — marks a striking evolution for the British monarchy.

After all, Queen Elizabeth II, Britain's longest-serving monarch, is on the throne only because divorce was unacceptable for the royal family not that long ago. Her accession was unanticipated: She was born in 1926 at the home of her maternal grandparents, not a royal palace. The daughter of the second son of a king in a system rooted in primogeniture, Princess Elizabeth was expected to marry well and have an unremarkable (though privileged) life. Her future, and history, changed when her uncle David fell in love with an American, Wallis Warfield Simpson, who had married not once but twice before she met the then-Prince of Wales.

The British government and dominions were adamant that a twice-divorced American could not be crowned queen, not when the king was head of the Church of England, which did not then allow divorcés to remarry during the lifetime of a former spouse. The new king, however, was equally adamant that he would not give up the woman he loved. He abdicated in 1936, catapulting his younger brother, and later his niece, to the throne, and he was exiled.

Days after Elizabeth's own coronation in 1953, another divorce scandal broke: Her sister, Princess Margaret, was in love with a divorced equerry, Group Capt. Peter Townsend. Officials and courtiers, still shaken by the abdication, were opposed. Margaret was told she could marry Townsend — if she renounced her royal rights and left the country for some years. She chose her royal position and eventually married someone else — whom she later divorced.

As fifth in line to the throne, Harry is not considered a future king. Still, he is a senior enough royal that he needs the sovereign's approval to wed — and in years past, permission would not have been granted to marry a divorcée (American or otherwise) without the prince renouncing his claim on the crown.

In some respects, the evolution is unexceptional: Public attitudes toward divorce have relaxed markedly in recent decades, and the share of marriages ending in divorce in England and Wales has risen. Three of the queen's four children have divorced.

Yet the speed with which the monarchy has shifted on divorce is remarkable for an institution that venerates tradition and symbolizes history. When Elizabeth's daughter, Anne, the Princess Royal, remarried in 1992, she did so in Scotland because she could not be remarried in a Church of England service.

When Prince Charles sought to marry his longtime love Camilla Parker-Bowles, things were complicated by the enduring popularity of his first wife, Princess Diana, and by Charles's position as heir to the throne — and future supreme governor of the Church of England. Although the church had begun allowing divorcés to remarry a few years earlier, finding clergy to conduct the ceremony was a challenge. Charles and Camilla married in a civil service, in a registrar's office in Windsor, and followed that with a blessing at St. George's Chapel, during which, in a nod to societal judgments, they acknowledged their "manifold sins and wickedness."

Charles's years-long campaign for public acceptance of Camilla and his insistence on marrying her set a precedent that made it easier for Harry, 33, to propose to 36-year-old Meghan, who was divorced in 2013.

Meanwhile, though Markle's ethnicity has drawn scrutiny during their relationship, it speaks volumes that a biracial American commoner is being warmly welcomed into Britain's royal family, itself the top tier of a class-conscious society. The acceptance of her class and racial heritage as simply part of a modern family also stand out at a moment when racial tensions and class divisions are so pronounced in the United States.

The queen saw the burden the crown placed on her father — who died at 56 — and she models her parents’ belief in prioritizing the monarchy before personal desires. Her reverence for tradition and her silence in the face of criticism sparked outrage in the aftermath of Diana’s death, when an empty flagpole at Buckingham Palace was a lightning rod for public upset.

But she is beloved in part for embodying Britain’s stiff upper lip and carrying on while saying little. Her stewardship over decades of deep social change has protected the monarchy as an institution above, yet reflective of, British life. She has guided the throne to a place where a woman who became sovereign as a result of a divorce scandal could welcome a divorced American into Britain’s royal family.