If they heard the boos, they certainly didn’t show it.
The Prince and Princess of Wales were greeted with chants of “USA, USA” as they attended a Celtics basketball game in Boston on Wednesday evening.
The couple sat courtside for the NBA match against Miami Heat but looked surprised when they appeared on the jumbotron during the second quarter.
They briefly waved, then chatted awkwardly, each glancing up at the giant screens to check if they were still on camera.
Amid loud cheers from the 20,000-strong crowd, an unmistakable sound of dissent rang out from some parts of the stadium, but the royals appeared unfazed, gamely fixing their smiles.
The smattering of boos was likely an anti-establishment protest in a city with strong Irish, Catholic links.
The Boston Celtics’ name was inspired by the Original Celtics, a well-known basketball team created by Irish immigrants in New York in 1914.
“If we lose we blame this on the British,” one Celtics fan tweeted. But they needn’t have worried. The home team, seventeen-time World Champions, won 134 to 121.
Earlier, the Prince and Princess lit up green Boston City Hall and other local landmarks.
A crowd of around 1,000 turned out in torrential rain to see the couple launch a three-day countdown to the Earthshot Prize ceremony.
On arrival in the city, the Prince paid tribute to his late grandmother, describing Queen Elizabeth II as “one of life’s optimists” before adding: “So am I.”
A Kensington Palace spokesman said “racism has no place in our society” but made clear there would be no further comment on the controversy as they focused on the job at hand.
On arrival at the basketball, the Prince and Princess stood for a rousing rendition of US national anthem, The Star Spangled Banner, sung by a semi finalist from reality television series The Voice.
The couple sat alongside Boston Celtics owner Wyc Grousbeck and his wife Emilia Fazzalari for the match, each talking animatedly throughout.
The Princess, wearing a blue jacket and black trousers, listened intently as she was talked through the game by Ms Fazzalari, while at one point, the Prince laughed as he held a basketball.
Joined by Governor elect Maura Healey and Boston Mayor Michelle Wu, they both clapped each point and appeared amused by the antics of the players.
Until their faces appeared on the big screens, many fans did not appear to have realised that they were in the company of royalty.
The Prince and Princess left their seats for refreshments during half time but returned for the third quarter. Aides had suggested they would leave at that point, but they opted to stay until the end, shaking hands with fans as they left.
The couple were at the match to promote the Earthshot Prize and there were several nods to the forthcoming award ceremony throughout.
Digital advertising boards were lit up green to promote the awards, while spectators were treated to a promotional Earthshot video.
After the second quarter, the royals watched as the Celtics honoured their long standing tradition of recognising a “Hero Among Us”, celebrating individuals working to positively impact the community.
Ollie Perrault, a 15-year-old climate activist from Easthampton, Massachusetts, was introduced to the couple after being cheered by the local crowd for her work as a leading member of the Youth Climate Leadership Programme.
She is now the founder and director of Youth Climate Action Now, committed to fighting for environmental justice, advocating for an intersectional system change, and working to get more young people involved in direct climate action.
Before the game, the Prince and Princess met members of the “Celtics family”, including representatives of the Boston Celtics Shamrock Foundation, which provides grassroots programming and strategic funding to local organisations serving at-risk or in need populations.