Important reason Princess Catherine won't be joining Prince William in Singapore

The Princess of Wales won't be joining Prince William during his trip to Singapore for a very important reason.

The Prince of Wales explained his wife's absence during a speech on Monday morning.

"Catherine is very sorry she can't be here," he said. "She is helping George through his first set of major exams."

Prince William is in Singapore for the third annual Earthshot Prize and for his United For Wildlife program. The royal launched the Earthshot Prize in 2020 to promote initiatives that address the most urgent environmental challenges.

READ MORE: King Charles hands Princess Anne new role

Kensington Palace previously confirmed that Prince William would travel to Singapore solo due to their son's exams.

This marks the first time that Princess Kate will miss the Earthshot Prize awards ceremony, which she has attended for the last two years in London and Boston.

READ MORE: CSI: Miami and My Sister's Keeper star Evan Ellingson dies at 35

Prince George is attending Lambrook School in Windsor along with Princess Charlotte, eight, and Prince Louis, five.

According to Hello!, Prince George is sitting for the ISEB Common Pre-Tests, taken by Year 6 students in the UK.

Prince George will sit for four tests – English, Maths, verbal reasoning and non-verbal reasoning.

Lambrook School runs up until Year 8 and then Prince George will likely attend Marlborough or Eton, both of which are boarding schools. Princess Catherine and her siblings attended Marlborough and Prince William attended Eton along with Prince Harry.

READ MORE: Adult Lego sets for the Lego superfan in your life

Princess Catherine reportedly visited Marlborough, according to a source who spoke to The Daily Mail.

"It's been the talk of the school," they added.

Prince George was also spotted visiting Eton with his parents earlier this year.

While Eton is located close to the family's Adelaide Cottage home, it is an all boys school where as Marlborough is co-ed.