Never-Before-Seen Photo of Kate Middleton from Her College Days Revealed Ahead of Her 40th Birthday

Never-Before-Seen Photo of Kate Middleton from Her College Days Revealed Ahead of Her 40th Birthday

Before Kate Middleton was one of the most photographed people in the world as the Duchess of Cambridge, she was a “shy” college student.

The Sun‘s royal photographer Arthur Edwards recently rediscovered the first photo he ever took of Kate, who will celebrate her 40th birthday on Sunday, and he admits, “I didn’t know who on Earth she was.”

Kate was pictured in 2005 with a group of friends who had been invited by Prince William to spend a weekend at Sandringham. In the photo, she’s dressed casually in jeans, a green jacket and a scarf, with her hair tied back into a low ponytail.

“Back then you would never have credited that the young woman who walked through those gates would turn out to be our future queen,” Edwards said.

Middleton Family/Clarence House via Getty

Middleton Family/Clarence House via Getty
Kate Middleton and Prince William in 2005
| Credit: Middleton Family/Clarence House via Getty

Kate and Prince William, 39, met as college freshmen at St. Andrews University in Scotland in 2001. At their 2005 graduation, the couple posed for a photo together in matching button-down white shirts.

Edwards recalled that after Kate and Prince William separated in 2007, it was his wife Ann who spotted Kate at a Wembley Stadium concert honoring Princess Diana. “I remember Ann saying to me: ‘Looks like it’s on again.’ “

Ahead of their 2010 engagement, Edwards was first introduced to Kate — and the photographer boldly asked Prince William about the split.

Prince William reportedly told him, “Well, Arthur, I had to be sure this was the right woman for me because I want this marriage to last forever.”

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Prince William; Catherine Duchess of Cambridge

Prince William; Catherine Duchess of Cambridge
Prince William and Kate Middleton
| Credit: Alex Bramall/Kensington Palace

The couple married in 2011 and the now parents of three celebrated their 10th wedding anniversary this past April, throughout which Edwards has seen Kate find her footing as a future queen consort.

“As the years go by she is changing, overcoming her natural shyness and becoming more confident,” Edwards said. “She is intelligent, pays great attention to detail and never gets it wrong.”

The Duchess of Cambridge is “flourishing,” a royal insider told PEOPLE ahead of Kate’s 40th birthday. “She has really come into her own.”

Kate is preparing more than ever for her role as future queen consort alongside William, taking on more royal duties as Queen Elizabeth has canceled engagements due to recent health issues as well as Prince Harry and Meghan Markle‘s decision to step back as senior working royals.

She is “more and more impressive as time goes on,” a source close to the royal household tells PEOPLE. “She is a focused and professional woman.”