The decision by the Duke and Duchess of Sussex to step back from senior roles in the royal family and split their time between North America and Britain has dashed hopes that their marriage marked a watershed in UK race relations.

The couple’s relationship and the birth of their son were heralded by some as hugely symbolic moments, given Meghan’s biracial heritage, which would help foster greater interest in the monarchy among black Britons.

But with Prince Harry and Meghan having announced plans to operate as “hybrid royals” after protracted run-ins with the press, including accusations of reporting with “racial overtones”, it appears the wider significance of their coupling may have been overplayed.

Sunder Katwala, the director of the thinktank British Future, said: “It’s a missed opportunity. It was putting a lot of pressure on Prince Harry and Meghan Markle: their relationship has to sort out race relations in the UK and fix the monarchy’s relationship with the public. But it was an opportunity for the royal family, it symbolised something different and it’s failed [to achieve what was hoped for].”

Polling by British Future before Harry and Meghan’s wedding suggested her biracial heritage would barely register with the majority of Britons but that it had more meaning for black and minority ethnic Britons, who were more likely to invest the marriage with significance than their white counterparts.

At the time the Labour MP David Lammy called it “a great new symbol of all that is still possible and hopeful in modern Britain”, while Doreen Lawrence, whose son Stephen was murdered by racists in 1983, said it was “amazing” that someone like Markle could join the royal family.

Katwala said black and minority ethnic Britons who saw it as a positive thing would now have questions to ask about the media treatment of Meghan as “someone who’s stolen away Prince Harry” and whether that treatment, consciously or not, was racist.

The joint winner of the 2019 Booker prize, Bernardine Evaristo, is one of a number of public figures who has blamed racism for the royal couple’s retreat. In the aftermath of the announcement, she tweeted: “Dear Meghan, my sister, do your thing with your family and get away from the race hate you’ve been subjected to in my country.”

Kehinde Andrews, a professor of black studies at Birmingham City University, was a sceptic from the start and said he had been proved correct. “It was never going to end well. The only surprise is that it’s happened this quickly.

“The speed of it just shows how incompatible blackness is with the royal family. I don’t think they specifically mentioned racism [in their announcement] but it’s pretty clear that they’ve been hounded by the press, even after she had a baby,” he said.

“A lot of the anti-Meghan stuff isn’t directly racist but that’s not how racism works these days. It’s clearly about racism, what else can it be about?

“This was never the change we thought it was – it was just symbolic.”