As theyfollowed in processiona coffin that carried their grandmotherQueen Elizabeththrough London on Wednesday,Prince WilliamandPrince Harrywalked a similar path to the one they took 25 years ago for the funeral of their mother,Princess Diana.

On September 6, 1997, William and Harry — then ages 15 and 12, respectively — followed a route that began at Kensington Palace, Diana’s London home, to Westminster Abbey.

“It was one of the hardest things I’ve ever done, that walk,” William said in the 2017 BBC documentaryDiana, 7 Days.“It felt like she was almost walking along beside us to get us through it.”

In the same film,Prince Harryrecalledhearing people screamingin the crowds that lined the London streets. “The broadcast news today still talks about the silence and of course there was a huge amount of silence, but what I remember is every 50 yards or whatever certain people in the crowd just unable to contain their emotion,” he said. “That was a big thing.”

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

Prince Charles

Bells tolled continuously then, as they did on Wednesday as the princes accompanied their father,King Charles III, and other members of the royal family on the procession ofQueen Elizabeth’scrown-toppedcoffin from Buckingham Palace to Westminster Hall, where the late monarch, who died September 8 at age 96, will lie in state until Monday morning.

STR/AFP via Getty

From the left, Prince William, Earl Spencer, Prince Harry and Prince Charles approach the gun carriage with the coffin of Diana, Princess of Wales in London 06 September during the funeral ceremony.

A mourner and member of the British public Jo Cadzow tells PEOPLE she had Diana’s sons on her mind as she watched the procession for the Queen. “I thought of those two men,” she said. “It must bring back memories for them 25 years [ago]. I have huge respect for them doing it.”

Prince William and Prince Harry.Chris Jackson/Getty Images

Prince William, Prince of Wales and Prince Harry, Duke of Sussex walk behind the coffin during the procession for the Lying-in State of Queen Elizabeth II

The decision to have William and Harry follow their mother’s coffin through the streets of London in 1997 was not made easily.

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Diana’s brother,Charles, 9th Earl Spencer, said in an interview with BBC Radio 4 20 years later that it was “cruel” to make the young princes walk behind the coffin and that he was against the plans.

JUSTIN TALLIS/POOL/AFP via Getty Images

Prince William, Prince of Wales (L) and Britain’s Prince Harry, Duke of Sussex follow the coffin of Queen Elizabeth II, adorned with a Royal Standard and the Imperial State Crown and pulled by a Gun Carriage of The King’s Troop Royal Horse Artillery

But friends of the royal family have said that it was William and Harry’s grandfather,Prince Philip, who told the young princes, “If I do it, will you?”

King Charles, Prince William and Prince Harry.DANIEL LEAL/POOL/AFP via Getty Images

King Charles III (L), Britain’s Prince William, Prince of Wales (2L) and Britain’s Prince Harry, Duke of Sussex walk behind the coffin of Queen Elizabeth II

Harry also recalled it being a “group decision” to have them follow Diana’s coffin on its journey through London.

“Before I knew it, I found myself with a suit on with a black tie and a white shirt, I think, and I was part of it,” he said “Genuinely, I don’t have an opinion on whether that was right or wrong. I am glad I was part of it. Looking back on it now, I am very glad I was part of it.”

William added that at the time, “I couldn’t understand why everyone wanted to cry as loud as they did and show such emotion as they did, when they didn’t really know our mother.”

Prince William, Princess Diana and Prince Harry.Getty

Princess Diana

“Now, looking back,” he continued, “I’ve learned to understand what it was that she gave the world, what she gave a lot of people.”

Cadzow, who lives in Warminster, said she was pleased to see members of the royal family process behindQueen Elizabeth’s coffin on Wednesday.

source: people.com