Prince George undertook his first royal duty by attending a Buckingham Palace tea honoring World War II veterans this spring, where he gave a glimpse of the leader he’s becoming.

George, 12, stepped into the spotlight like never before when he joined his parents, Prince William and Kate Middleton, at a May 5 palace event hosted by King Charles.

Dressed in a dark suit and blue tie, Prince George asked former service members thoughtful questions —“Did you see any U-boats?” and “How many flight missions were you on?”— about their wartime experiences in a deeply meaningful appearance.

“This was the first sign of George taking on future duties,” Russell Myers of The Mirror tells PEOPLE in this week’s exclusive cover story. “Even though he is so young, he seems to have grown in confidence over the last couple of years.”

Myers adds that the young prince was “very engaged” alongside Princess Kate at the tea honoring veterans, which marked his most formal royal duty to date.

“That is quite a responsibility to sit down and chat with veterans like that,” adds a palace insider. “It was incredible.”

For observers, the moment highlighted how the Prince and Princess of Wales, both 43, have been carefully preparing their eldest son, who turned 12 on July 22, for the throne one day.

“It’s a slow game, and it gets him used to it on the couple’s terms rather than anybody else’s,” says the palace insider.

While his younger siblings, Princess Charlotte, 10, and Prince Louis, 7, often steal the spotlight with their lively charm, Prince George tends to project a more thoughtful calm at public events.

“He comes across as a serious chap,” the insider says. “To have the world’s eyes on you, especially when you’re so young, is demanding.”

Yet those who know him best say he also has a playful streak, and he is also a big brother and a schoolboy with a close-knit circle of friends. Now on the cusp of his teens, he is being gradually introduced to the royal role he will one day inherit.

Following a summer in which his mother has been regaining strength nearly a year after chemotherapy, Prince George is returning to Lambrook School in September for his final year alongside Prince Charlotte and Prince Louis. Unlike previous heirs, he has always attended coed day schools, in a break from past generations.

“That chimes with William wanting to do things in a more modern way, putting all three children in the same school,” says royal author Sally Bedell Smith. “It’s a new direction — groundbreaking for the royal family.”

The pivotal decision of where George will continue his education next year lies ahead, and Eton College, the all-boys boarding school where William thrived, is considered the front-runner. It’s also conveniently close to his family’s new home, Forest Lodge in Windsor Great Park, where they plan to settle by year’s end.

At Forest Lodge, William and Kate plan to maintain the routines that matter most: school drop-offs and pickups, sports games and everyday family moments — all without live-in staff. The Prince and Princess of Wales have succeeded in giving their children a childhood largely outside of the limelight, putting family first.

“William takes his role as father of the future King as seriously as he takes his role as future King. That’s key,” says royal biographer Robert Hardman. “His overarching priority is making sure they enjoy it rather than fear it.”

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With King Charles still undergoing treatment for an undisclosed form of cancer, questions about the future are inevitable. If George becomes heir to the throne before finishing school, William may delay bestowing him with the traditional Prince of Wales title.

“They would want him to focus on having freedom before giving him any royal titles,” the insider says.

Indeed, times have changed. King Charles was called “Sir” at school, while Prince William went by his first name and George is following suit.

“It’s evolution, rightly so,” notes the close insider, reflecting the modern vision William is defining for his son.