Prince and Princess of Wales are bombarded with cheers of 'USA' and a smattering of boos at Boston Celtics basketball game - one hour after black Reverend gave lecture on 'colonialism and racism' at Earthshot launch amid Palace race row

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The Prince and Princess of Wales joined 20,000 fans to cheer on the Boston Celtics at a basketball game - just after the launch of the prince's Earthshot Prize risked being overshadowed by a Buckingham Palace race row. 

On their first day in the city during a landmark US tour, William and Kate were brought into the TD Garden stadium to sit courtside close to the action alongside the Celtics' owners Wyc Grousbeck and wife Emilia Fazzalari.

Kate and William, who were also flanked by Massachusetts Governor-elect Maura Healey and Boston Mayor Michelle Wu, stood for the US national anthem, The Star-Spangled Banner, performed by a previous semi-finalist from the reality TV series The Voice.

The royal couple put on brave faces as faint boos could be heard around the arena when they were introduced by a stadium announcer and shown on the big screen. 

Other fans in the crowd could be heard loudly cheering 'USA, USA' when the Prince and Princess appeared on the screens above the court. 

But the royal couple kept smiling and took photos with fans. They cheered on the high-scoring game as the packed crowd ramped up the atmosphere for the 17-time World Champions game against the Miami Heat. 

The Boston Celtics' name was inspired by the Original Celtics, a well-known basketball team created by Irish immigrants in New York earlier in the 20th century, before folding in 1930.

Sitting courtside, William and Kate ended up with a basketball as the team warmed up before the game

The Prince of Wales looked like he was enjoying himself as he cheered on the Boston Celtics, with Kate flashing him a smile

The couple had the best seats in the house for the basketball game between the Boston Celtics and the Miami Heat

The royal couple take a picture with Emilia Fazzalari, wife of the Celtics owner, on Wednesday night 

They greet and take photos with fans during the Boston Celtics game on Wednesday night, despite the furore at Buckingham Palace

William and Kate appear on the jumbotron at TD Garden and wave to the crowd as faint boos could be heard in the stadium

William and Kate share a private moment as they walk down the side of the court at the Celtics game on Wednesday

William and Catherine, Prince and Princess of Wales, pose with fans during the NBA game

From left to right, former Celtics player and coach Tom 'Satch' Sanders, Prince William and Kate, Princess of Wales, watch an NBA basketball game between the Boston Celtics and the Miami Heat in downtown Boston

Celtics owner Steve Pagliuca, his wife Judy, Mayor of Boston Michelle Wu, Governor-elect Maura Healey, Prince William, Catherine, Princess of Wales, Emilia Fazzalari, wife of Celtics owner Wyc Grousbeck, and Wyc Grousbeck stand as they listen to the US national anthem

Before the game, the royals met members of the 'Celtics family', including representatives of the Boston Celtics Shamrock Foundation, which provides grassroots programming and funding to local organizations serving at-risk or at-need populations.

Around the arena, digital advertising boards were lit up green to promote Prince William's Earthshot awards, while spectators were treated to a promotional video ahead of the game.

After the second quarter with the game tied 47 all, William and Kate watched as the Celtics honored their long- standing tradition of recognizing a 'Hero Among Us', highlighting individuals working to positively impact the community.

Ollie Perrault, a 15-year-old climate activist from Easthampton, Massachusetts, got to meet the royal pair after being cheered by the local crowd for her work as a leading member of the Youth Climate Leadership Program.

She is now the founder and director of Youth Climate Action Now, committed to fighting for environmental justice, and working to get more young people involved in direct climate action.

Aides had suggested the royal couple would depart after the third quarter of the game, but they decided to stay until the end, shaking hands with fans as they left the stadium.

William and Catherine, Prince and Princess of Wales, talk with their hosts, Boston Celtics owners Wyc Grousbeck and his wife Emilia Fazzalari (R) following the NBA game between the Boston Celtics and the Miami Heat

Prince William talks with former Boston Celtics player Satch Sanders during the second half of an NBA basketball game

Celtics owner Steve Pagliuca, former Celtics player and coach Tom 'Satch' Sanders, Prince William and Catherine, Princess of Wales attend the Wednesday night National Basketball Association game between the seventeen-time World Champion Boston Celtics and the Miami Heat at TD Garden in downtown Boston

Prince William, Prince of Wales and Catherine, Princess of Wales, watch the NBA basketball game between the Boston Celtics and the Miami Heat

Prince William, Prince of Wales and Catherine, Princess of Wales watch the NBA basketball game

William and Catherine attend the NBA game between the Boston Celtics and the Miami Heat

The Prince and Princess of Wales attend the Wednesday night National Basketball Association game between the seventeen-time World Champion Boston Celtics and the Miami Heat at TD Garden in downtown Boston

Prince William, and Catherine, Princess of Wales attend the Wednesday night National Basketball Association game between the seventeen-time World Champion Boston Celtics and the Miami Heat

William and Kate applaud players at the Celtics game on Wednesday night, and they decided to stay until the end of the game

William and Kate watch the big screen during the Boston Celtics game at the TD Garden on Wednesday 

Prince William in particular looked to be having fun, clapping and cheering on the team

Prince William and Kate Middleton - with Boston Celtics owner Wyc Grousbeck and wife Emilia Fazzalari - were seen grinning and cheering as they sat courtside at a Boston Celtics game on Wednesday night, just one hour after their Earthshot Prize launch was dragged into the royal race row

There is no doubting that William and Kate had hoped the evening's match - the second in their official list of engagements during their whirlwind three-day trip to Boston - would go off without a hitch, given the awkward moment at the Earthshot launch just hours before the game.

As the Prince and Princess Wales watched on from the wings at the launch event, African-American Reverend Mariama White-Hammond, who founded a youth organization focused on 'teaching the history of the civil rights movement', said: 'On this day, I invite us all to consider the legacy of colonialism and racism.'

She referenced 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. 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.'

It came after Lady Susan Hussey, former lady-in-waiting to the Queen and William's own godmother, was accused of making racist comments to black domestic abuse campaigner Ngozi Fulani at a Buckingham Palace event on Tuesday night.

Although there was no direct reference to Lady Susan, few could fail to connect the controversy with Reverend White-Hammond's remarks.

Prince William and Kate Middleton meet 15-year-old climate activist Ollie Perrault after she received her award at the Celtics game Wednesday

William and Kate smile as Celtics team members horse around in front of them during the game on Wednesday 

William and Kate watch as the Miami Heat take on the Boston Celtics in Boston on Wednesday

Having started her speech by 'acknowledging the ancestral lands we stand on today', the Reverend went on to express gratitude to William and Kate for choosing to host this year's Earthshot Prize in Boston.

'Now you all know we are a city of many firsts. We are honored to be the first American city and the first city outside of the United Kingdom to host the Earthshot Prize,' she continued.

Her comments about colonialism came just months after another of William and Kate's international engagements - a March tour to the Caribbean to mark the Queen's Platinum Jubilee - attracted controversy due to accusations that elements of it smacked of 'colonialism'.

Ambassador Caroline Kennedy and Secretary John Kerry were both scheduled to attend the Earthshot event this week, but were no-shows at the last minute. 

Kerry, the presidential envoy for climate, informed the Prince and Princess earlier today that he would 'sadly no longer be able to attend,' but did not clarify why.

Kennedy, the daughter of President John F Kennedy who is currently serving as the US Ambassador to Australia, said she experienced 'disrupted travel plans' due to the harsh weather lashing the east coast.

But there were very few cancellations at airports in Boston and in New York due to the weather, according to FlightAware. 

William and Kate at the Earthshot Prize opening ceremony with Governor-Elect Maura Healy on Wednesday evening

William and Kate visit Boston City Hall on Wednesday evening during the Earthshot Prize ceremony

Reverend White-Hammond, who spoke at the launch, founded a youth organization that focused on teaching the history of the civil rights movement

Caroline Kennedy and John Kerry both failed to show up for Prince William and Kate Middleton's Earthshot event in Boston on Wednesday evening 

This week Prince William will also visit the John F Kennedy Presidential Library and Museum.

He and his wife will learn about the work that local organisations are doing to mitigate the risk of rising sea levels in Boston and they will also tour Greentown Labs, in the nearby town of Somerville, to get an insight into the development of innovative green technologies. 

There are also plans for the royal couple to meet President Joe Biden on Friday, who will be in Boston on a separate trip.