Katie Couric recalls the moment she broke down in tears while covering Princess Diana's funeral

• Katie Couric has revealed why she broke down in tears while covering Princess Diana's funeral.
• Couric was struck by an envelope with "Mummy" written on it from Prince Harry on Diana's casket.

Katie Couric has revealed the moment that made her break down in tears while she was reporting live from Princess Diana's funeral.

Couric flew to London to cover the event for NBC in September 1997. She details the difficult day in her new memoir, "Going There," which was released on Tuesday.

"Bereft Londoners and tourists were leaving bouquets outside the gates," Couric said of the scene at Westminster Abbey, where the service was held. "By midweek, they'd cover acres."

Couric was seated on a platform directly across from the church's entrance with Tom Brokaw. When the procession came into view, she saw that Prince William and Prince Harry - then aged 15 and 12 - were walking behind their mother's casket.

"The casket, laden with lilies, had a simple white card on top that said 'Mummy' - handwritten and placed there by Harry," Couric wrote. "Mourners wailed at the sight of the princes walking behind the casket, heads bowed."

The moment especially struck Couric as her own husband, Jay Monahan, had been diagnosed with colon cancer. He would die a year later at the age of 42.

"I realized that what I was seeing was not the passing of the most famous woman in the world," Couric continued. "It was two boys who'd lost a parent. And I thought of my girls."

Couric said she couldn't fight back the tears. She whispered to Brokaw, "I'm having a really hard time."

"He put his hand on my back and nodded - he understood," she wrote. "So did the control room, which instructed the cameraman to get a two-shot of Tom and Tina while I wiped my face and tried to pull myself together. Diana and Jay - I was mourning them both."

Couric met Princess Diana for the first time just 15 months before her death.

The veteran TV journalist sat next to the princess during a June 1996 luncheon for breast cancer research at the Drake Hotel in Chicago.

Couric said she asked Princess Diana if she was "excited to go home" after such an exhausting trip in the US.

"I would be, but I'm going home to an empty house," replied Princess Diana, who was in the midst of finalizing her divorce from Prince Charles.

Couric said she was surprised by Diana's "openness" and "sensed a deep sadness" from the princess.

"At the time, I had no idea how miserable she really was," she added.