"It has to be significant. The fact of someone black being married into the royal family represents a widening and a diversion and an inclusion that it's never had before," Walters told Reuters as she shopped in Brixton, south London.
"I'm still not pro-monarchy at all because I don't think anybody is born to rule. However, I do understand symbolism and this is very powerful."
The upcoming marriage of the British prince, sixth-in-line to the British throne, to Markle, whose father is white and mother is African-American, has been heralded as demonstrating how Britain has become more egalitarian and racially mixed.
Just 60 years ago, marrying a divorcee was considered unacceptable for a British royal, and only in 2013 did it become permissible to wed a Catholic without being removed from the line of succession.
So Markle's entry into an exclusively white royal family, who wield hugely emotional symbolic power in Britain, should not be underestimated, said Afua Hirsch, author of "Brit(ish): On Race, Identity and Belonging".
"It represents a real change in the messaging to young people growing up in Britain and that idea that blackness and Britishness are mutually exclusive," she told Reuters.
"I think for me when I was younger that would have made a huge difference to me psychologically in my sense of legitimacy and confidence that this is my country."
"RIVERS OF BLOOD"
The wedding comes at a time race issues have been prominent in Britain. Last month saw the 25th anniversary of the murder of black teenager Stephen Lawrence by white racists which led to London's police force being labelled institutionally racist by an inquiry due to its botched handling of the case.
It was also 50 years since the infamous "Rivers of blood" speech by politician Enoch Powell in which he warned that "the black man will have the whip hand over the white man" if immigration was not stopped.
The British government has also found itself mired in a scandal about treatment of some descendants of the "Windrush generation" of Caribbean migrants who were invited to Britain after World War Two but have been left without documents and denied basic rights.
Markle, whose maternal ancestors were slaves, and Harry attended a memorial service to mark the Lawrence anniversary and there has been much commentary about how attitudes have changed since the days of Powell. But others say the Windrush episode betrays the true picture.
"(The wedding) means nothing. It really is a non-event in terms of what it means for society," Kehinde Andrews, an associate professor of sociology at Birmingham City University and author on race issues. He described racism "as British as a cup of tea".
"What on earth could we possibly be celebrating in the fact that there's a splash of coffee in the premier symbol of whiteness in the UK?
"That's for me the problem with a lot of the coverage of this wedding. The monarchy is an institution. Adding a black face, one black face, one very light-skinned, pretty black face is not going to change the institution."
A survey for the British Future think-tank last month suggested most Britons would barely notice Markle's ethnicity and the vast majority welcomed it.
However, 12 percent of those questioned thought someone of mixed race marrying into the royal family was bad and 25 percent would be uncomfortable with their child to having a serious relationship or marrying someone of a different race.
It also found 33 percent of ethnic minority respondents thought racial prejudice was as high as when Lawrence was murdered. In a TV interview last month, London mayor Sadiq Khan, who is a Muslim, said most institutions in Britain had "problems with institutional racism".
"STRAIGHT OUTTA COMPTON"
One story about the Los Angeles neighbourhood where Markle's mother Doria Ragland lives carried the headline "Harry's girl is (almost) straight outta Compton: Gang-scarred home of her mother revealed" while Rachel Johnson, sister of British Foreign Secretary Boris Johnson, wrote she would bring "rich and exotic DNA" to the Windsors.
Asked about such focus in a TV interview to mark their engagement last November, Markle said such coverage had been "disheartening".
"But I think you know at the end of the day I'm really just proud of who I am and where I come from and we have never put any focus on that, we've just focused on who we are as a couple," she said.
In the street market in Brixton, where many Windrush immigrants settled and which has a large black population, the overwhelming view of the royal marriage was positive, some likening it to Barack Obama becoming America's first black president.
Those reactions echoed the warm reception the engaged couple received when in January they visited Brixton, an area that became synonymous with inner city deprivation following race riots in 1981.
"I think it's good for the nation to see somebody like her marrying in the royal family," transport worker Noel Davis, 60, told Reuters.
Rhianne Fleming, 23, said: "I think it's going to be exciting, especially the fact that she's mixed race.
"It shouldn't be that important. But the historical context ... I guess it is a bit of a 'Wow, oh my god this is happening' when it shouldn't be," she added.
Hirsch said younger people she had spoken to admired Markle.
"They are interested in this royal wedding in ways they have never been in previous royal weddings," she said. "Because there is something there who looks like them, like somebody they are close to, whose mother resembles somebody they are close to."
However, for Andrews and others, it just showed how bad the situation is.
"Markle is not Britain's Obama moment and shouldn't be covered as such. Being chosen by a prince is not democracy," author Reni Eddo-Lodge wrote on Twitter after the engagement was announced.
"Because racism is so bad and so historic and so entrenched that we tend to look for things, anything," Andrews said. "So any symbol that could possibly be good we tend to over-celebrate. But when we sit back and actually analyse what's happened and what's changed, we'll realise it means nothing at all.
"The serious issues of entrenched racism, unemployment, all these issues that really face us, the monarchy is part of the problem and she's now part of the problem not the solution."
For many on the streets of Brixton though, race was ultimately not the main issue of the wedding.
"If the people love each other, then it doesn't matter if they are royal or common," Walters said. "It's love that matters."
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
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