Kate Middleton and Prince William Host Prince Haakon and Princess Mette-Marit of Norway at Windsor Castle

Kensington Palace Kate Middleton and Prince William and Princess Mette-Marit and Prince Haakon of Norway

It was a meeting of two future kings at Windsor Castle on Thursday.

Prince William and Kate Middleton got reacquainted with counterparts from Norway, Crown Prince Haakon and Crown Princess Mette-Marit, at a meeting on Thursday during the Norwegian royal couple's visit to the U.K. Haakon and Mette-Marit planned to visit the U.K. in September, but their visit was rescheduled due to Queen Elizabeth II's death. King Harald and Queen Sonja of Norway attended the state funeral service for the late monarch at Westminster Abbey.

It was a reunion for Prince William, 40, and Princess Kate, 41, who spent time with Prince Haakon and Princess Mette-Marit, both 49, during a visit to Oslo in February 2018 — but this time, Prince William is also next in line to the throne.

The Prince and Princess of Wales hosted Crown Prince Haakon and Princess Mette-Marit for the Windsor Castle meeting, where they focused on discussing shared concerns about the environment, their office at Kensington Palace said. After their meeting with the Norwegian royal couple, all four of them sat down with representatives from three leading companies from Norway who are working on green energy solutions.

Kensington Palace

Around the table at the meeting with the royal couples was Alex Grant, Senior Vice President and UK Country Manager, Equinor, Øivind Eriksen, CEO, Aker ASA, and Børre Jacobsen, Managing Director, Northern Lights JV. Also joining them was His Excellency Wegger Chr. Strømmen, Norwegian Ambassador to the U.K.

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In 2018, Prince William and Kate bundled up for a winter tour to Sweden and Norway. Their trip included a visit a visit to Holmenkollen resort, which is home to the Holmenkollen Ski Jump, one of Oslo's most famous landmarks.

Crown Prince Haakon and Crown Princess Mette-Marit also visited in the U.K. in November 2018 to attend the then-Prince Charles' 70th birthday party at Buckingham Palace.

Victoria Jones - Pool/Getty Prince Haakon, Princess Mette-Marit, Prince William and Kate Middleton in 2018

It comes after a busy week of public engagements for Prince William and Princess Kate. On Tuesday, they headed to Wales for a series of outings, including unveiling a program to build vegetable gardens to promote mental well-being and visiting a sports center to highlight the good work being done there and the role fitness can play in positive mental health.

William was also announced as royal patron of Wales Air Ambulance, when they met with a base at Llanelli, in the west of the country.

Alastair Grant - WPA Pool/Getty Images Prince William and Kate Middleton

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On Wednesday, the couple was on duty handing out ceremonial leeks and meeting soldiers and their families at the annual St. David's Day parade at Windsor's Combermere Barracks.