Camilla 'Never Contemplated Becoming Queen,' Says Biographer: 'It's a Hell of a Challenge at This Age'

"Queen Camilla" was not a title the one-time Camilla Parker Bowles ever imagined holding. But on May 6, at age 75, Camilla will officially be crowned Queen alongside her husband, King Charles, at his historic coronation.

"Considering that for most of her life she'd never contemplated the idea of becoming Queen, she's doing incredibly well," Christopher Wilson, royal biographer and author of A Greater Love, tells PEOPLE in this week's issue. "It's a hell of a challenge being permanently in the spotlight at this age, but she's tough and can take it."

Camilla and Charles met in 1970 through mutual friend Lucia Santa Cruz and discovered an undeniable connection. The then-Prince of Wales was encouraged to find a virginal bride, so Camilla went on to marry army officer Andrew Parker Bowles, and Charles wed Princess Diana — although their romance continued.

After Princess Diana famously said "there were three of us in the marriage," the press branded Camilla Parker Bowles "the most hated woman in Britain." In the aftermath of Prince Charles and Diana's divorce in 1996 and Diana's tragic death in 1997, Charles' staff worked to remedy Camilla's image as the "other woman."

By 2005, public opinion had changed enough that the couple felt confident to marry, and they recently celebrated their 18th wedding anniversary.

"She is quite steely," a source close to the royal household tells PEOPLE in this week's issue. "She went through a lot to be by his side." Royal photographer Arthur Edwards, who has followed the royals for The Sun for 45 years, adds that Camilla's warmth and wry humor always brings out the best in Charles.

"She never lost her common touch," Edwards tells PEOPLE. "She makes him laugh. When something triggers them, you see them just laughing together. They do things with such enthusiasm."

Camilla's devotion to Charles and enthusiasm for duty inspired Queen Elizabeth's last Accession Day message, where she shared it was her "sincere wish" that Camilla be known as Queen Consort when Charles became King. But their bond wasn't always so strong; the Queen, a deeply religious woman and head of the Church of England, previously struggled with Camilla's status as a divorced woman and the nature of her relationship with her eldest son.

Once the marriage was sanctioned, Camilla was accepted at royal events. Through the years, she and the Queen shared a mutual love of country life, and the sovereign respected her dedication to her royal responsibilities.

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Camilla supported her husband through the death of his mother in September 2022 and is now poised to take her place beside him and be crowned as Queen on May 6.

"They work well as a team. It's impressive," Wilson tells PEOPLE of Charles and Camilla. "Her presence reassures him. Despite all the trappings of majesty, it's cold and lonely at the top, and it's easy to see the comfort she provides him."