'It's all you': How Prince William has always celebrated Kate's popularity...after Earl Spencer claimed Charles was 'extremely jealous of Diana's star power'

While King Charles is believed to have become resentful of Diana's popularity, the Prince of Wales has always been happy for Kate to take the spotlight. 

Nowhere is this more evident than a resurfaced clip of Prince William and Kate from 2012, when the future Queen was pregnant with her firstborn, Prince George.  

Royal fans swooned over the moment Prince William told his wife, 'it's all you' after they stepped onto the balcony of The Guildhall during their first official visit to Cambridge as the Duke and Duchess of Cambridge on November 28, 2012. 

The crowd erupted in loud cheers as Kate, radiant in a pale pink coat dress, stepped onto the balcony beside Prince William. 

Seemingly delighted by the love for his wife, the future King broke into a smile before telling Kate in no uncertain terms that she was the reason for their adulation in a private moment that perfectly encapsulates their love story. 

It is in stark contrast to Earl Spencer's claim that Charles was 'extremely jealous of Diana's star power' in his new book, Swan Song. 

Royal fans swooned over the moment Prince William told his wife, 'it's all you' after they stepped onto the balcony of The Guildhall during their first official visit to Cambridge as the Duke and Duchess of Cambridge on November 28, 2012

The late princess' younger brother, whose book sparked a bitter war of words with Buckingham Palace over claims the King said 'we'll forget Diana soon enough', identified their 1983 tour of New Zealand and Australia as the turning point. 

'While most husbands would have been delighted and proud to have such an asset for him and his royal brand, the [then] prince was extremely jealous of Diana's star power.

'That much had been clear since the day in Sydney, in 1983, when Diana's huge popularity with the Australian crowd had riled her husband.' 

He wrote that Diana, then 21, 'craved' Charles's 'support and approval'  - only to be met with an 'envy she found perplexing and unfair'. 

Buckingham Palace accused Earl Spencer of 'grief clouded reasoning' after his incendiary claims about the days following Diana's death were revealed by the Mail. 

The Palace issued an extraordinary statement that said: 'While we do not comment on books as a matter of principle, His Majesty is mindful that the pain of fraternal grief can cloud reason, affect judgment and colour memory in ways others do not recognise, even many years after such a loss.' 

During his marriage to Diana, the now-King allegedly felt sidelined on several occasions after it became clear his bride was the rising star in the royal family. 

Fans queued for hours to see her over the then-heir to the throne, Charles, on their joint engagements.

So popular was Diana that, during the couple's first joint royal tour of Wales after becoming the Prince and Princess of Wales, Charles even admitted to crowds of adoring fans that his wife was the person they had come to see.

Throughout their marriage, Diana continued to steal the limelight from Charles as she shone in the public eye with her keen eye for fashion, striking beauty and her deep compassion for others.

It is in stark contrast to Earl Spencer's claim that Charles was 'extremely jealous of Diana's star power' in his new book, Swan Song

After millions around the world tuned in to watch the wedding of Charles and Diana, the couple took their first trip to Wales as a married couple in October 1981.

While many people around the world were mesmerised by the young Lady Diana on her wedding day, this trip is widely recognised as the first time the then-Princess of Wales won over the British public as she shone while her husband stood in her shadow.

Throughout the visit, royal fans were keen to meet the newlyweds - but had a particular fondness for Diana. As the couple visited people in communities with high unemployment and new mothers on maternity units, members of the public were struck by Diana.

Archive footage of the visit shows the couple being greeted by crowds, who can be heard chanting: 'We want Princess Di!'

The Princess's popularity was so stark, it even prompted Charles to tell some royal fans: 'There's the person you've come to see,' ITV reports.

Two years later, the royal couple travelled across the world to visit Australia and New Zealand for the first time in a joint engagement.

Once again, Diana's star shone brighter than her husband's, as royal fans were desperate to catch a glimpse of the Princess over Charles.

In fact, the contrast in popularity was so stark, it was dramatised in an episode in series four of The Crown, where Josh O'Connor's Charles shouts: This was supposed to be my tour!' at Emma Corrin's Diana.

As a fictional depiction of real-life events, it is a scene that exaggerates the tensions between the pair. 

However, the angry exchange is derived from an obvious wedge that had been driven between the couple during the 1983 visit, which may have been down to Diana's soaring popularity.

The 40-day tour of Australia and New Zealand took place against an already tense background, as the royal visit clashed with a growing republican movement across Australia and serious calls were being voiced for the nation to leave the Commonwealth. 

There were also concerns about new mother Diana taking Prince William with her, as she did not want to be separated. 

However, aside from a few awkward moments upon arrival, Princess Diana was once again lauded by the local press during the tour, which saw the couple span 30,000 miles.

The Sydney Morning Herald said of Diana: 'Despite the predictions, Diana, apart from some strain and tiredness, has fared well. She might be made of tougher stuff than many think.'

And as the tour continued it became clear that Princess Diana was the star of the show, with Charles walking in her shadow.

A news report from ABC at the time noted how communities in the Riverland had 'come to see' Diana - while also noting her professionality.

The broadcaster said: 'The Princess seemed more anxious to meet the people than did her husband. She dispensed tidbits concerning Prince William’s health, the weather, and jokingly inquired of an elderly citizen if she had any whiskey in her picnic basket,' as reported by Vogue.

Clips from the trip showed adoring fans holding up signs for Princess Diana, calling her 'beautiful'.

Cracks soon began to appear in Charles and Diana's marriage, with the Prime Minister John Major announcing their divorce in the House of Commons in December 1992.

Following the couple's separation, Princess Diana's popularity remained high among members of the public, who still gathered in swathes to meet her during appearances where she carried out charity work following her divorce.

Up until Diana's tragic death in 1997 in a car crash, she remained popular, with her death itself prompting an outpouring of grief from an adoring British public, who lined the streets to pay their respects during her funeral procession.