LONDON — Prince William and his wife Kate fly out to the United States on Wednesday for their first visit for eight years, as an intense media spotlight on the British royal family and the sons of King Charles shifts across the Atlantic.

The U.S. trip will be the new Prince and Princess of Wales' first overseas excursion since the death of Queen Elizabeth, which meant William - Charles's eldest son - became the heir to the throne.

The visit has gained added significance as it comes a few days before William's Los Angeles-based younger brother Prince Harry and American wife Meghan take the limelight at a prestigious awards ceremony ahead of a Netflix TV documentary and revealing memoir.

William and Kate will visit Boston, primarily to attend an awards ceremony for the Earthshot environmental prize which the prince set up. It is being viewed by the royals as a trip rather than a more traditional tour.

The last time they visited the United States in November 2014, they were guests of then-President Barack Obama at the White House.

This visit will be lower key: they will visit local environmental, educational and community projects in Boston, although the Earthshot ceremony itself will be a star-studded event with the likes of Grammy-winning singer Billie Eilish and Oscar-winning actor Rami Malek.

"Our number one focus... is the Earthshot Prize and we won't be distracted by other things," a source close to William said.

During their three-day stay, William, 40, and Kate, 40, will visit the John F. Kennedy Presidential Library and Museum where they will meet Caroline Kennedy, the daughter of the former president and now U.S. Ambassador to Australia.

A few days later, Harry and Meghan, the Duke and Duchess of Sussex, will go to New York for the Robert F. Kennedy Ripple of Hope Award where they will be honoured for their commitment to social change and human rights work, in a group which also includes Ukrainian President Volodymyr Zelenskiy.