Prince William and Kate Middleton
Prince William and Kate Middleton both attended the inaugural Earthshot Prize Awards in London on Sunday, Oct. 17, 2021. Photo by: Max Mumby/Indigo/Getty Images Max Mumby/Indigo/Getty Images

Prince William revealed why Kate Middleton is not with him in Singapore for the Earthshot Prize Awards in a speech on Monday, saying her absence is due to an important family reason.

The Princess of Wales opted to remain in the U.K. to help with their children's studies. She especially stayed behind to assist their eldest child, Prince George, with his school exams.

"Catherine is very sorry she can't be here. She is helping George through his first set of major exams," he said during a speech at the United for Wildlife summit.

A Kensington Palace spokesperson previously confirmed that the 41-year-old would be travelling to Singapore solo because of the young prince's exams. This marks the first time that the Princess of Wales has missed the Earthshot Prize Awards, which she has attended for the past two years.

The inaugural ceremony was held in London in 2021 and the second in Boston in December 2022. Prince William launched the Earthshot Prize in 2020.

In his speech, Prince William also recalled his last visit to Singapore 11 years ago with Kate Middleton, saying that it had been "memorable". They visited the country on behalf of Queen Elizabeth II during her Diamond Jubilee year.

The Prince of Wales likewise shared his joy to be back in the country in a statement posted on X. He wrote: "Singapore's bold vision to be a leader for environmental innovation sets the standard for others to follow. I am grateful to the Singaporean people for hosting us this week. Let us all take inspiration from the fantastic work being done here as we celebrate this year's Earthshot Prize finalists."

The future monarch's first stop was at the Jewel, a nature-themed entertainment and retail complex connected to one of the airport's passenger terminals. The complex, which opened in 2019, houses the world's tallest indoor waterfall called the HSBC Rain Vortex flocked by verdant trees and terraced gardens.

Ahead of the Earthshot Prize Awards on Tuesday, he also participated in a dragon boat contest. He shared a video from the event and commended the sport for bringing in different communities together.

"Out on the water with British Dragons! Great to see the power of sport in bringing communities together, with rowers from Singapore, Britain and across the Commonwealth enjoying the amazing camaraderie of their dragon boating team," he wrote.

Joining Prince William at the Earthshot Prize Awards are a few celebrities including Cate Blanchett, who is also an Earthshot Prize Council Member, actress Lana Condor ("To All The Boys I've Loved Before") and Robert Irwin, the son of the late Steve Irwin. Hosting the event are three-time Emmy Award winning actor and producer Sterling K. Brown and "Ted Lasso" actress Hannah Waddingham.