Noor Inayat Khan was not what one would expect of a British spy.

She was a princess, having been born into royalty in India; a Muslim, whose father was a Sufi preacher; a writer, mainly of short stories; and a musician, who played the harp and the piano.

But she was exactly what Britain’s military intelligence needed in 1943.

Khan, whose name was in the news in Britain recently as a proposed new face of the £50 note, was 25 when war was declared in 1939. She and her family went to England to volunteer for the war effort, and in 1940 she joined the Women’s Auxiliary Air Force and trained to become a radio operator.

Able to speak French, she was quickly chosen to go to Paris to join the Special Operations Executive, a secret British organization set up to support resistance to the Germans from behind enemy lines through espionage and sabotage.

Khan was the first female radio operator to be sent by Britain into occupied France, according to her biographer, Shrabani Basu.

Khan had worked hard to overcome her fear of weapons during combat training and improved her ability to translate Morse code, but colleagues in her intelligence network still had doubts. Some wondered if she was too young and inexperienced. They pointed out that she had carelessly left codes lying around and that she had unthinkingly revealed her British background by pouring milk into cups before the tea.

They also questioned whether she had the right sensibility for the job, having been raised under Sufism, a mystical form of Islam.

“Not overburdened with brains but has worked hard and shown keenness, apart from some dislike of the security side of the course,” a superior officer, Col. Frank Spooner, wrote in her personal file. “She has an unstable and temperamental personality and it is very doubtful whether she is really suited to work in the field.”

Still, she had excellent radio skills, which the special operations unit desperately needed, so in June 1943, she was sent to France, where she assumed the name Jeanne-Marie Renier, posing as a children’s nurse. Madeleine was her code name.

Within 10 days of her arrival, all the other British agents in Khan’s network had been arrested. The SOE wanted her to return to Britain, but she refused, saying she would try to rebuild the network on her own.

She ended up doing the work of six radio operators. She moved constantly to evade detection and dyed her hair blonde to avoid being recognized. She knocked on the doors of old friends, asking them if she could use their homes to send messages to London from a wireless set that she carried around in a bulky suitcase.

Her work had become crucial to the war effort, helping airmen escape and allowing important deliveries to come in.

“Her transmissions became the only link between the agents around the Paris area and London,” Ms. Basu wrote in her biography “Spy Princess: The Life of Noor Inayat Khan.”

In recognition of her bravery and service, she was awarded the George Cross by Britain and the Croix de Guerre, with gold star, by France.

Noor-un-Nisa Inayat Khan was born on Jan. 1, 1914, in Moscow to Hazrat Inayat Khan and Ora Ray Baker, an American who had changed her name to Amina Sharada Begum after her marriage. Khan’s father, a musician and philosopher who was known as Inayat Khan, was in Moscow at the time on an extended stay with his group, the Royal Musicians of Hindustan, who had been invited to perform in Russia.

Her father was also a descendant of an 18th-century ruler of the Kingdom of Mysore, in southwest India, making Noor a princess. Inayat Khan was raised in Baroda, in west India, but left the country to introduce Sufism to the west. (He met his future wife while lecturing in San Francisco.) Sufism emphasizes the renunciation of worldly things, purification of the soul and the mystical contemplation of God’s nature.

During World War I, the family moved to Paris and then to London, where Noor’s three siblings were born. The family returned to Paris in 1920 and eventually settled in Suresnes, west of the city.

Inayat Khan died while on a pilgrimage in India. With her mother overwhelmed by grief, Noor, at just 13, was left to look after the family.

Even as she managed the house, Noor wrote short stories, dedicated poems to the family and enrolled at École Normale de Musique de Paris. She also studied child psychology at the Sorbonne.

After finishing school, Khan produced an English translation of the Jataka Tales, fables about the previous incarnations of the Buddha, and established herself as a writer. Her book “Twenty Jataka Tales” was published in 1939.

Khan never made it home from the war. Just as she was about to leave for England in October 1943, she was captured by the Gestapo.

She tried to escape but was caught and sent to a German prison in Pforzheim, on the edge of the Black Forest, where she was chained in solitary confinement, fed the smallest rations and beaten.

On Sept. 12, 1944, she was sent to the Dachau concentration camp and tortured there. She and three other S.O.E. women were executed the next day. She was 30.

Her cousin Mahmood Khan Youskine remembered her as a refined and dainty young woman who had told him charming stories about rabbits and urged him to play the piano.

“The remarkable thing was, within that fineness was also that steely strength of will,” he said in a telephone interview, the “kind of attitude that she displayed in her military career toward the Germans.”

He attributed her determination to her upbringing in the Sufi tradition.

That sense of duty is also evident in her writing, said her nephew Pir Zia Inayat-Khan, who has helped get her work, including a retelling of Homer, published.

“The theme of sacrifice comes up again and again in her writing,” he said by phone. “It’s as if she had already anticipated her own martyrdom.”

Khan will not be the next face of the £50 note; the Bank of England has announced that the subject will be a scientist, replacing the likenesses of the steam engine pioneers James Watt and Matthew Boulton. (The selection will be announced in 2020.) But awareness of Khan’s wartime efforts, in part because of the £50 note publicity, has grown.

English Heritage, a British group that celebrates notable people in history, is planning to create a traditional blue plaque for Khan, adding her to a long roster of figures whose plaques appear on buildings in which they lived or worked. In France, a primary school in Suresnes has been named after her. In 2014, PBS made her the subject of a documentary, “Enemy of the Reich: The Noor Inayat Khan Story.” And the writer Arthur Magide is working on another biography of her.

In Gordon Square in London, where Khan once lived, there is a statue of her in a quiet corner. It is engraved with the last word she reportedly said before being executed at Dachau — “Liberté.”

© 2018 The New York Times Company