It was understated, perhaps even a touch informal. 

But when five young future monarchs from Western Europe gathered for a photograph at the birthday celebrations of the Danish prince Christian, it was quite a moment – not least because four of the five were female.

Changes to primogeniture laws mean that, for the first time, the future of monarchy across Europe is female, and among the queens will be Princess Elisabeth of Belgium, Duchess of Brabant – who turns 22 today.

Destined to be the first queen of her young nation, she has been directly affected by the legal change, made in 1991. In earlier times, her younger brother Gabriel would have been the monarch.

Princess Elisabeth in a new portrait released to celebrate her 22nd birthday today

Future monarchs from around Europe gather for the 18th birthday celebrations of Prince Christian of Denmark. From left to right: Princess Estelle of Sweden, Princess Ingrid Alexandra of Norway, Prince Christian, Princess Catharina-Amalia of the Netherlands , and Princess Elisabeth of Belgium

Princess Elisabeth of Belgium during a gala dinner on the occasion of the 18th birthday celebrations of the Danish Prince at Christiansborg Palace in Copenhagen

Princess Elisabeth is the eldest of King Philippe and Queen Mathilde of Belgium ‘s four children

Born on October 25, 2001, Princess Elisabeth is the eldest of King Philippe and Queen Mathilde of Belgium’s four children.

When her father became King in 2013, Elisabeth became the heir to the throne and Duchess of Brabant.

Elisabeth began attending royal engagements from a young age and was just nine when she delivered a speech at the opening of the Princess Elisabeth Children’s Hospital.

Like a number of other European royals, including Princess Leonor of Spain and Princess Alexia of the Netherlands, Elisabeth attended Atlantic College in Wales before moving on to Oxford.

Nicknamed ‘Hippie Hogwarts’, the school curriculum has included unusual activities such as Tai Chi and Tibetan literature. It has a remarkable cliff-top location in a 12th-century castle in the Vale of Glamorgan.

Elisabeth enrolled on a £67,000, two-year course to study for her International Baccalaureate diploma at the school, which she has now completed.

Before her two-year course in Wales, she attended the Dutch-speaking secondary school Sint-Jan Berchmanscollege in Brussels. 

The Princess also went to the Yale Young Global Scholars Program at Yale University. 

She then completed a one-year course in social and military sciences at the Royal Military Academy which is said to teach in-depth about the four components of Belgian defence: Army, Air Force, Navy and Medical.

When her father became King in 2013, Elisabeth became the heir to the Belgian throne and Duchess of Brabant

When Elisabeth ascends to the throne after her father, she will make history as she becomes Belgium’s first-ever Queen

She gave her name to the Belgian scientific research station Princess Elisabeth Antarctica Research Station in 2011

Having been preparing for a life in the spotlight since birth, Elisabeth began attending royal engagements from a young age

Elisabeth began attending royal engagements from a young age and when she was just nine

In 2021, she was photographed at the Lagland camp in Arlon, where she marched in formation with her fellow cadets.

For the officer cadets of the Royal Military Academy, this camp is part of the last training phase for first year students, and constitutes part of the Initial Military Phase. 

Alongside her training, in October 2021, the Princess began studying History and Politics at Lincoln College, Oxford. Here, she rows for Lincoln College Boat Club under the name ‘Elisabeth de Saxe-Coburg’.

According to Belgian newspaper Le Soir, the princess completed a written entrance exam in history ‘anonymously’ so that her social status would not affect her marks.

Elisabeth is believed to have chosen the course herself, in agreement with her parents, and reportedly consulted with graduates from various universities and made her decision based on what would be most useful to her in her role as queen later in life.

The high-achieving Princess, who is fluent in Dutch, French, German and English, recently completed two years at the Royal Military Academy’s annual three-week summer camps and other practical and theoretical military classes.

On Tuesday, she took part in the ceremony of taking the oath as an officer – swearing ‘loyalty to the King, obedience to the Constitution and the laws of the Belgian people.’ 

Alongside her training, in October 2021, the Princess began studying History and Politics at Lincoln College, Oxford

Elisabeth has completed three years of intense training at the Royal Military Academy

After the ceremony on Tuesday, she joined her family to pose for photos, where she was seen beaming proudly as she stood alongside her father, the King

In snaps from the event, the Princess appeared serious as she took part in the ceremony – marching and saluting to the King alongside her comrades from the 160th Promotion of Social and Military Sciences.

Afterwards, she joined her family to pose for photos, where she was seen beaming proudly as she stood alongside her father, the King.

An accomplished 21-year-old by any measure, the official royal website says Elisabeth enjoys walking in nature, reading and playing the piano – although like ‘all youngsters her age’, writes the palace, ‘her taste in music is varied.’