In the 1980s and '90s, Diana became associated with compassion, warmth, humility and glamour, while King Charles, who was then the Prince of Wales, was a more reserved and perhaps slightly more awkward figure.

In 2022, a quarter of a century after Diana's tragic death, a YouGov poll found 72% of the British public had a positive view of the late princess, while 67% had a positive view of King Charles.

The monarch is now preparing for his coronation on Saturday 6 May as he seeks to shape his legacy as King.

With William and Harry now championing many of their mother's causes, and Diana remaining a much-loved figure, many will be wondering whether the King will always remain in the shadow of the "people's princess".

Younger people 'not as familiar with Diana'

Royal commentator Richard Fitzwilliams told Sky News: "The important thing to bear in mind is that so many years have passed since Diana's tragic death, and also a whole generation who never knew her.

"Diana did some truly remarkable things. She was an amazing human being. She was deeply flawed and complex and also she helped others in a unique way.

"But with King Charles set to be crowned and as we look to the future, younger people are not as familiar with Diana as those in their fifties or whatever."

The death of Diana in a car crash in Paris in August 1997 was followed by an outpouring of grief around the world.

In turn, the popularity of the Royal Family was diminished as the Queen was seen as too slow to issue a public address or make a statement on the tragedy.

King Charles, who many felt had treated Diana badly throughout their marriage, had to rehabilitate his image as the princess became just as iconic in death as she had been in life.

Mr Fitzsimmons believes the King's reputation has largely recovered, but there are now fresh challenges facing the monarchy.

"The nineties were so disastrous for the Royal Family. There were those who didn't think it would survive but it has proved to be durable.

"In recent years there have been real problems with the Sussexes and with Prince Andrew in disgrace.

"I think they are far more pressing concerns for those who appear most disillusioned with the royals."

'Diana was anything but conventional'

During their marriage, Diana undoubtedly found it easier to connect with the public than the future King and was credited with humanising the British monarchy.

She also became closely associated with humanitarian causes such as advocacy against landmines and fighting stigmatisation around HIV/Aids.

Asked why so many people felt able to connect with Diana in a way they didn't with King Charles, Mr Fitzsimmons says: "First of all she was younger, she was glamorous, and she had the magic touch.

"She was able to reach out to people.

"The then Prince Charles was doing an amazing amount of work, for example for his Prince's Trust, but he was doing conventional royal duties, whereas Diana was anything but conventional - hence the magic.

"Diana was also an expert in PR and Charles was not at that time. He has been in rehabilitating Camilla, but that's another story."

'He'll always be living under that cloud'

In the days before the King's historic crowning ceremony at Westminster Abbey, Mr Fitzsimmons believe it is too early to say what the monarch's legacy will be.

The royal commentator said there is "talk of a slimmed-down monarchy" and the Royal Family will have to stay relevant, diverse and contemporary.

"The dispute or the rift with the Sussexes is a great blow in that regard."

Despite the new challenges facing the King, there are those who believe Diana's legacy will always be a problem for him.

Tom Bower, a royal expert who wrote the book "Rebel King: The Making Of A Monarch" about King Charles, told Sky News: "He'll always be living under that cloud and under the legacy and the tragedy of Diana's death and their awful marriage. That is his fate."

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Mr Bower added that Charles lacks "charisma" and the "sort of mystery magic" which Diana had and that helped "spark a sense of love" for her from the public.

"She was beautiful and she was vulnerable and she was charismatic. She had qualities which Charles doesn't have. And she appealed especially to women and to a certain group of men."

Mr Bower says the monarch also has a problem due to the fact that he is an "old man".

"His misfortune is he is combating simultaneously the legacy of Diana with older people, and in his seventies, he is struggling to connect with the younger generation.

"He is caught between the two."