A black reverend has given a lecture on equality as she opened William's Earthshot Prize awards hours after the Prince's godmother engulfed the Royal Family in a race scandal.
The Prince and Princess of Wales arrived in the US for a three-day trip which will culminate in him attending the awards he founded to promote solutions to environmental challenges.
But the event has been overshadowed after William's godmother and senior courtier Lady Susan Hussey was forced to resign over comments to a black woman that have rocked the monarchy.
Ngozi Fulani, who was born in the UK and runs a black women's domestic abuse charity, said the royal aide asked her: "Where do you come from?"
In a conversation that followed, Hussey continued to ask "what nationality are you?", "where do your people come from?" and "what part of Africa are you from?"
Buckingham Palace released a statement condemning the "unacceptable and deeply regrettable comments" and confirmed she had "stepped aside from her honorary role with immediate effect."
Ngozi told the Mirror: "[What she did] was racism. Through and through. It was prolonged racism.
"The fact that it was just done in the open in front of people, on a day when we should be working towards violence against women."
Ngozi also said Hussey told her: "I can see I am going to have a challenge getting you to say where you're from. When did you first come here?"
Eventually, Ngozi says she replied: "I am a British national, my parents came here in the 1950s," before Hussey responded with: "Oh, I knew we'd get there in the end, you're Caribbean."
Ngozi says she then corrected the aristocrat by responding with: "No, I am of African heritage, Caribbean descent and British nationality."
Several hours after the news was announced that Hussey had stepped down later William and Kate listened on awkwardly at a civic event in Boston with pastor Reverend Mariama White-Hammond speaking.
She urged the crowd to "consider the legacy of colonialism and racism" when dealing with environmental issues.
"The ways it has impacted people across the world and its connection, its deep connection to the degradation of land and our planet that we are all seeking to reverse," she said.
"The stories lost, the species made extinct, but also the persistence of people in the face of oppression and the fundamental dignity of all of our relations.'
No mention was made of the controversy or either person involved.
William also spoke at the rainy outdoor event at City Hall Plaza, which saw him and Kate switch on a set of green lights to illuminate the centre of Boston.
He thanked the "hardy Bostonians braving the rain this evening" before giving a speech hailing the influence of John F Kennedy's 'Moonshot' speech on his own project.
He said: "It was that Moonshot speech that inspired me to launch the Earthshot Prize with the aim of doing the same for climate change as President Kennedy did for the space race.
"And where better to hold this year’s Awards Ceremony than in President Kennedy’s hometown, in partnership with his daughter and the Foundation that continues his legacy."
