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Princess Of Wales In Hong Kong Wearing An Outfit Described As The Elvis Look Designed By Fashion Designer Catherine Walker

Princess Dianaleft a huge impression on the royal family, includingQueen Elizabeth.

“Diana was the first person to rattle the cage of the monarchy within living memory,” the Queen’s biographer Ingrid Seward tells PEOPLE in this week’s issue, which looks back at Diana’s legacy 25 years after her tragic death on Aug. 31, 1997.

“I don’t think Diana went out intentionally to change the family,” Seward, who knew Diana personally, adds. “She did it because that was the way she was.”

Princess Diana, Prince Charles and Queen Elizabeth.getty

Queen Elizabeth Sporting the Crown Through the Years

The Queen was criticized for staying silent in the days that followed Princess Diana’s death.

“It felt pretty perilous,” says Ed Perkins, director of the new HBO documentaryThe Princess.

On the evening of Sept. 5, the monarch finally addressed the nation — as both “your Queen” and “as a grandmother” — in a rare televised speech. Despite her usual stoic nature,Queen Elizabethappeared to realize that she needed to express emotion…following Princess Diana’s lead.

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In recent years, the 96-year-old Queen has shown her ability to express warmth, even participating in comedy skits like at the2012 Olympicswith Daniel Craig as James Bond andsharing the screen with Paddington Bearfor her Platinum Jubilee earlier this summer.

“Who knows whether an event like that could have happened without someone like Diana coming in?” says Perkins.

Adds Seward: “The Queen can now see Diana’s legacy is a huge force for good.”

source: people.com