All eyes will be on the royals and their choice of outfits for King Charles III’s coronation as the historic day rapidly approaches.

The dress code for the May 6 ceremony will be a “massive change to royal protocol,” according to King Charles’ former butler Grant Harrold.

“This event is going to be so completely different to Queen Elizabeth II’s coronation when it comes to dress codes,” he told Slingo. “Aristocracy traditionally would wear the coronation robes.”

“If you look at the Queen’s coronation, you would see the dukes, duchesses, countesses all had these special robes that were created for the coronation,” he continued. “Historically, these robes were worn by the aristocracy, but now this will not be the case.”

“For this coronation, most royals will wear suits, not their special robes,” said Harrold, 45, who worked for the King from 2004 to 2011, when the now-monarch was Prince of Wales.

“This is a massive change to royal protocol. The senior members of the royal family decide the royal etiquette and dress code — they are always changing etiquette as they’re the ones who decide all the changes which will then be accepted as another part of the royal protocol,” he shared.

Elsewhere, Harrold is sure that the female royals will opt for dresses on the big day.

“I believe the ladies will wear dresses. For the evening event they might wear ball gowns, but during the day they will obviously wear something very smart,” he predicts.

“I don’t think you will see the Princess of Wales, the Duchess of Wessex or the Duchess of Edinburgh wear any tiaras. I really don’t think we’ll see that in the dress code because I think the focus will be more on day wear, showing how relaxed the dress code is for the event.”

Elsewhere, Harrold said he thinks King Charles and Queen Camilla will continue on with the tradition of wearing ceremonial robes for the event.

“No question, not at all. I also think the King will most likely wear a crown during the ceremony,” he added.

His opinion differs from that of various sources, who believe the King will scrap the “dated” look of the past and instead “break away from tradition.”

“We’ll see the men in suits and uniforms,” he notes, adding that the royals will follow “a modern dress code instead of the traditions.”

For more Page Six Style you love …

Harrold believes that guests at the ceremony, of which will be around 2,000, will wear day dresses and accessorize with hats, which Harrold notes “will be protocol.”

Last week, Kate Middleton, the Princess of Wales, hinted at what fans can expect her to wear on May 6.

The royal, who is married to Prince William — the heir to the throne, teased that there’s “a hint of blue” in her coronation outfit.