MADRID — Among the next generation of young European royals, Spain's Princess Leonor has seen her popularity soar as she turns 18.

In a gesture that went viral, Spain's Princess Leonor broke protocol on 12 October.

At the celebration of Spain's national day, the princess was surprised by her classmates from the military academy she had just graduated from.

As the cameras rolled, one of the cadets said to the princess: "How beautiful you look, Borbón", a compliment that brought laughter from King Felipe and Queen Letizia and a smile of complicity from Leonor.

In that natural and human moment, she could have been any teenager, but Leonor de Borbón has rarely been seen to break protocol.

From that point on, the whole of Spain has been paying more attention to the ever move of a princess destined to become the first queen of Spain in the modern era.

On her 18th birthday on Tuesday, when she will swear allegiance to the Constitution, her popularity has soared, and Spain is gripped with 'Leonormania'.

But the surge in her popularity has some people asking whether the princess is simply blessed with natural charm, or whether her behaviour is all part of a plan to create the perfect queen.

With her innocent face, blue eyes and permanent smile, Princess Leonor has managed to win over the Spanish people.

She has even succeeded in renewing the image of the royal house and silencing some of the voices critical of the actions of her controversial grandfather, former King Juan Carlos.

The retired king's elephant hunting expedition, his secret stache of cash in Switzerland, and the harassment lawsuit filed by his former lover Corinna Larsen caused his popularity to plummet, dragging the crown down with it.

However, Leonor has been able to reconcile the Spanish with the Crown.

While it's difficult to know the level of support for the princess, as the Spanish Sociological Research Centre hasn't asked about the royal family since 2015, there are other private barometers that take an interest in the question.

The latest of these, published this week in El Español newspaper, ranks the young princess as the most popular member of the royal family, surpassing even her father Felipe VI, the current King of Spain.

Many Spaniards are succumbing to "Leonormania" and some experts suggest that her success is due to the fact that she has been out of the limelight for so many years. The lack of knowledge about Leonor means that now everyone wants to know who she is.

"The royal family have got their timing right. While she was studying, the princess was very reserved in her appearances," Fernando Rayón, journalist and professor of political information at the CEU San Pablo University, told Euronews.

"However, after the military academy and about to turn 18, a new Leonor has appeared, more mature and dressed as a soldier. A rather striking image," he adds.

For the expert, the excitement surrounding Leonor is not an opinion, but a fact.

The charisma she possesses, combined with her discretion, her prudence and an organisation that leads her to prepare and outline in a notebook the events in which she participates, have made normality the quality that most defines her. This allows the Spanish people to identify with her.

Support for Leonor is so widespread that, according to Hola magazine, only 21% of Spaniards think the princess is not well prepared for her role as head of state.

Her success has led many to wonder if Leonormania was created by the Zarzuela Palace's communication team.

"The image that Leonor gives is that of being where she needs to be. She makes no statements, there are no gratuitous images of her at home or partying. That's why people see her for what she is: the future Queen and Head of State," says Rayón.

Her authenticity may be the key to winning the hearts of Spaniards. Despite the royal family's tight control over communications, the princess's undoubted appeal is real.

"We have seen in the past that communication campaigns with other members of the royal family have not gone well. Image campaigns are very carefully studied, a series of requirements and appearances have to be met," explains Rayón.

"However, what has been done with Leonor is exactly the opposite: they have protected her from these communication campaigns," he adds.

Non-verbal communication expert José Luis Martín Ovejero agrees with Rayón and believes that Leonor does not need a communication campaign because she attracts people's sympathy on her own.

"Both through her communication - her verbal and non-verbal behaviour - she always shows that she is very natural and happy. You never see rude gestures or bad manners, not because these images are censored, but because she is not like that," says Ovejero.

Little is known about what Leonor is like in private and what she likes to do in her spare time, but her importance on the national stage has skyrocketed.

The non-verbal communication expert claims that the princess is in the spotlight more than her predecessors because the media were not able to reach the public as much as social networks do now.

And this is reflected in a 37% increase in Google searches related to Leonor, according to consultancy firm José Noblejas.

Although experts predict that Leonor could be the most charismatic European princess, at a national level she will have to win over the political parties and groups that are very hostile to the royal family - including politicians who will not be attending her swearing-in ceremony on Tuesday. — Euronews