When Prince Harry announced his engagement to actress Meghan Markle, the world rejoiced—and immediately began to analyze what it will mean for a biracial woman to take a prominent place as a British royal. Markle, whose mother is African-American and whose father is white, was celebrated by some as Britain’s first “black princess,” a milestone for a royal family that had presided over centuries of slavery and colonialism.

But the residents of Buckingham Palace may not be as white as is commonly assumed. According to some historians, mixed-race marriages among European royalty often went unacknowledged due to racism within both the royal family and European society at large. Indeed, Markle may not actually be the first black member of the British monarchy.

Charlotte of Mecklenburg-Strelitz, who married Britain’s George III in 1761, was also black, claims historian Mario Valdes. He says Charlotte was related to Margarita de Castro y Sousa, a black member of the Portuguese royal family.

However, much of the supposed evidence of Charlotte’s race is based on accounts of her face: she was widely considered to have the features of a person of African descent. During her reign as Queen Consort, Charlotte was mocked for her looks and described as having “a true Mulatto face.” Sir Walter Scott wrote that Charlotte’s family was filled with “ill-colored, orang-outang looking figures,” and during her coronation ceremony her relationship to “the warlike Vandal race”—an ancient Germanic tribe that lived in North Africa—was said to be preserved in her appearance.

It’s possible that those who found Charlotte ugly simply used racial stereotypes to insult her. But Valdes maintains she was actually black and had dark skin and features consistent with someone of African descent. However, this doesn’t show up in contemporary portraits or even caricatures of the queen. To Valdes, that’s proof of the literal whitewashing of history.

But other historians “argue the generational distance between Charlotte and her presumed African forebear is so great as to make the suggestion ridiculous,” writes The Guardian’s Stuart Jeffries. “Furthermore, they say even the evidence that [her Portuguese relative] was black is thin.”

Black royalty has always existed, and modern monarchies exist throughout Africa. But in Europe, monarchy had generally been reserved for members of elite white families. In the time of George III, who signed legislation abolishing the British slave trade, having a black wife would have complicated contemporary debates about race and slavery. Charlotte’s race—real or imagined—“inserts blackness into the heart of British femininity, beauty, and identity,” writes Paul Youngquist, a scholar who researches the portrayal of Africa in the British Romantic era.

So what do royals themselves have to say about Queen Charlotte’s background? In 1999, reports The Washington Post, a spokesperson for Buckingham Palace said that “This has been rumored for years and years. It is a matter of history, and frankly, we’ve got far more important things to talk about.”

In any case, Markle won’t be the first member of a modern mixed-race marriage. Modern members of the Habsburg family and royalty from Liechtenstein and Monaco have also married black women.

Though Markle is open about her racial identity and has been outspoken about the discrimination faced by herself and her family, expecting her to be an advocate for black and mixed-race Britons may be a stretch. “She won’t be allowed to be a black princess,” sociologist Kehinde Andrews told Newsweek. “The only way she can be accepted is to pass for white.”

Georgia Chambers, a British journalist who is also mixed-race, agrees. Holding up Markle, who straightens her hair and has fair skin, as an example of British racial tolerance “excludes many of us who do not have this commonly assumed “beauty privilege,” she writes.

Markle may be open about her racial identity, but it will take more than a few isolated mixed-race relationships within the British monarchy to break through the United Kingdom’s troubled legacy of slavery, colonialism, and racism.