In a meeting with the king, you would be expected to do a curtsey, a bow or a handshake. 

That is what the official royal website says is usually done. 

But in an unexpected moment of warmth this week, King Charles broke tradition when meeting the New Zealand Women Rugby team by accepting a group hug. 

"A hug? Why not!" the king said when Black Ferns winger Ayesha Leti-I'iga asked him. 

In a moment of surprise and delight, the rest of the rugby team rushed to join in. 

"It was like being flattened by a scrum," he joked with the team while smiling widely. 

The king is set to visit Australia next month on a royal tour with Queen Camilla. 

So is hugging Charles on the table if you're lucky enough to meet him?

So, how did it happen?

The beginning of the video showed the team nervously preparing to meet Charles at Buckingham Palace on a visit to play in England. 

"Do we have to bow or curtsey?" a player was heard asking. 

"What the heck a curtsey?" Ruby Tui asked looking panicked. 

When Charles entered the room, the outside back decided to go in with a handshake and said, "Sup G, how are ya?"

But her team member, Leti-I'iga, decided to try her luck for a hug. 

"It is such a stark contrast to the way people have greeted royal individuals in the past," Giselle Bastin, an associate professor at Flinders University, said. 

"No-one would have ever dreamed of asking the late Queen Elizabeth II for a hug, let alone for her to have said, 'Yes, why not.'"

"I think Charles is, despite undergoing treatment for cancer, he's in a very happy place, and I think he's enjoying being king, and when faced by this vibrant group of New Zealanders he thought, 'Yeah, why not.'"

The king later thanked the team for the "healing" embrace. 

"I've much appreciated meeting all of you and to have such a warm hug."

What is protocol for meeting a royal?

There actually isn't an official protocol for meeting a member of the royal family. 

The official website for the royal family says that "there are no obligatory codes of behaviour when meeting a member of the Royal Family but many people wish to observe traditional form".

For men, this is a neck bow from the head only, while women do a small curtsey. 

People can also shake hands in the "usual way".

But a hug is still very unusual. 

"Normally, you're not supposed to touch a royal unless they touch you," royal correspondent and expert Juliet Rieden said.

"We are in new times, you would never have seen the queen hugged by a member of the Black Ferns, it was very much off bounds."

But she said she wasn't surprised how receptive the king was to the offer. 

"The king is a very warm and friendly person, so I'm not surprised he looked so happy to receive it.

"[But] It does break ground."

Can people hug the king when he arrives in Australia?

There will be several opportunities for the public to come across the king.

The full itinerary of the visit is here. 

Ms Rieden said it is certainly possible people might be after a hug if they come across Charles. 

"I think a lot of it is affection for the king at the moment, especially in the knowledge he is going through cancer treatment and is still out there working," she said. 

"I think there is admiration for that, and that might run to Australians who will want to meet him, and shake his hand and greet him because it's been a tough year."

She pointed to the infamous photograph of Charles being intercepted by a model on a beach in Perth during a 1979 visit to Australia. 

The 26-year-old placed her hands on the royal's shoulders and surprised him with a kiss on the cheek. 

"King Charles, when he was Prince Charles, he's had lots of hugs, kisses on beaches.

"Perhaps it reminded him of his youth."

But there are of course security concerns. 

"I suspect it has the potential to get out of hand and people will want to jump in on the new royal thing," Dr Bastin said. 

"I'm sure Charles himself will see it as a step too far for it to become the norm." 

"We're more informal when adhering to royal protocols, but at the same time I don't think it will be a big group hug wherever Charles goes."

New generation of royals more relaxed with affection 

Ms Rieden said more casual and affectionate gestures have been seen by new generations of royals such as Harry and Meghan and the Prince and Princess of Wales, William and Catherine.

“I think it has opened that door to the human side of the monarchy, which is obviously very good for the brand and you don’t see anything cynical in it, and they’re just reacting naturally," she said. 

But this wasn't always the case. 

"Before, with the queen and Duke of Edinburgh, there was a lot more formality and I think that was a generational thing.

"Going back to how the monarchy was seen, and also how people were seen.

"Many people didn't get hugs from their parents, and it was a lot more formal relationships, especially in the upper classes."

'The Lizard of Oz'

Rare physical touch from members of the public toward royals was not always as positively received.

Prime Minister Paul Keating earned the name "The Lizard of Oz" after breaking royal protocol by putting his arm around the queen during her 1992 tour of Australia.

"The headlines were ridiculous and people went mad," Ms Rieden said. 

"It seemed to be the public and the press that were more concerned about it."

When is the royal tour of Australia?

The highly anticipated visit will see the king and queen in Canberra and Sydney from October 18 to 23.

Events at Parliament House in Canberra and on Sydney Harbour headline the tour, six years after the couple's last trip down under.

The prime minister will host a reception for Charles and Camilla on Capital Hill with Australian political and community leaders before they take part in a solemn wreath-laying ceremony at the Australian War Memorial.