"With a second, I realized what was happening," driver Colin Tebbutt tells PEOPLE

Two decades after the death of Princess Diana, her loyal driver still recalls the moment that made him crumple with grief in her Paris hospital room.

Following the princess’s death in a car crash on August 31, 1997, Colin Tebbutt was one of two of Diana’s staffers who were dispatched to Paris to prepare to bring her body home to Britain.

Upon finding the room at the Pitié-Salpêtrière hospital bustling with medics and other people – including the then-French President coming and going — Tebbutt helped secure it and ordered fans to cool the stiflingly hot late-summer temperatures.

“I plugged the fans in to the room to get some air circulating. I look round, and the eyelids and the front of the hair of the Princess were moving,” he previously told PEOPLE.

“I thought, ‘God, she’s alive,'” he adds. “Within a second, I realized what was happening. Turned around, a couple seconds to myself, I managed to get it together again. But that was the one bit when I felt I lost myself.”

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Credit: Jayne Fincher/Princess Diana Archive/Getty

Tebbutt had been alerted in the middle of the night to Diana’s fatal crash and quickly mobilized to join her butler Paul Burrell in heading to Paris. They were followed later that day by Prince Charles and Diana’s sisters, Lady Sarah McCorquodale and Lady Jane Fellowes.

Lady Sarah had been talking about having a quiet, private funeral. But so great was the welcome by crowds lining the roads as the hearse drove back into London that they quickly realized the need for something much bigger. There were “people upon people upon people all the way in,” Tebbutt recalls.

Prince Charles
From left: Prince Philip, Prince William, Charles Spencer, Prince Harry and Prince Charles walk behind Princess Diana's casket at her 1997 funeral
| Credit: JEFF J. MITCHELL/AFP/Getty

For Charles Spencer, the “hardest part” of the September 6 funeral day “was walking behind my sister’s coffin with her sons,” he says. “[Prince] Harry was this tiny little thing. And I was just so worried, you know, what a trauma for a little chap to walk behind his mum’s body. It’s just awful. I tried to stop that happening. But it wasn’t going to happen.”