Sansom arrived in France on the night of 3/4 November 1942 to work as a courier with the Spindle network (or circuit) of SOE headed by Peter Churchill (whom she later married).

Odette Marie Léonie Céline Brailly was born on 28 April 1912 at 208, rue des Corroyers in Amiens, France;[2] the daughter of Emma Rose Marie Yvonne née Quennehen[a] and Florentin Désiré Eugène 'Gaston' Brailly,[b] a bank manager, killed at Verdun shortly before the Armistice in 1918 and posthumously awarded the Croix de Guerre and Médaille militaire for heroism.

[7][6] As cover for her secret work, Sansom was enrolled in the First Aid Nursing Yeomanry, which supplied SOE with support personnel.

[7] Originally Sansom was considered too temperamental and stubborn by SOE, with an evaluation stating "She is impulsive and hasty in her judgments and has not quite the clarity of mind which is desirable in subversive activity.

[5] George Starr, one of SOE's most successful agents and a self-described martinet, called Sansom "a dreadful lady" and deplored what he portrayed as her seductive behaviour.

[9][10] Lise de Baissac, who trained in the same SOE class, said Sansom always wanted to be the centre of attention and often compared herself to Joan of Arc.

With Sansom stranded in Cannes, Churchill obtained Buckmaster's permission to scrap her original mission and for her to act as his courier.

[4][5] Sansom, posing as "Madame Odette Metayer", was required to find food and lodging for Rabinovitch, who was in France illegally and had no ration card, as well as to tend to air drops that were sometimes carelessly placed in dangerous areas.

They were joined there by several other members of the Carte network and SOE, a gathering which attracted the attention of the Italian fascist police and the Gestapo.

[12] SOE agent Francis Cammaerts visited Annecy briefly in March or early April 1943 and assessed the security of Churchill and Sansom's network as deficient and likely to be penetrated by the Germans.

[13] Meanwhile, in Paris in mid-March, spy-catcher Hugo Bleicher, an Abwehr counterintelligence officer, arrested Marsac, persuading him and another Carte associate, Roger Bardet, that he was an anti-Nazi German colonel and that they should work together.

At 2:00 a.m. on April 16, Bleicher, no longer in the guise of "Colonel Henri", appeared in the hotel with Italian soldiers and arrested Sansom and Churchill.

[22] Bleicher occasionally appeared and suggested that they might go to concerts and visit restaurants together in Paris, in return for which he hoped she could be induced to talk.

[23] After the Allied landings in the south of France in August 1944, on orders from Berlin, all food was withdrawn for a week, all light was removed from Sansom's cell, and the heat was turned up.

[23] When the Allies were only a few miles from Ravensbrück, the camp commandant Fritz Suhren forced Sansom into his car and drove to the advancing Americans to surrender.

Her torture was carried out by a "very good-looking young Frenchman" who she believed was mentally ill.[6] Sansom testified against the prison guards charged with war crimes at the 1946 Hamburg Ravensbrück Trials, which resulted in Suhren's execution in 1950.

"[29] In 1955, she co-founded the annual Women of the Year Lunch with Tony Lothian and Lady Georgina Coleridge (journalist and daughter of the Marquess of Tweeddale).

[27] Sansom, known as Odette Churchill after her marriage, gained considerable fame after the publication of a 1949 biography[31] and a film on her war work and prison ordeal in 1950.

[35] Documents disclosed long after the war indicate that her superiors had to fight for Sansom's George Cross, because she was unable to prove that she had been tortured by the Nazis and that she had not betrayed her fellow agents.

A manifesto signed by about 20 former associates accused Churchill of being in France only to collect material for a book about his experiences and asked what acts of sabotage he and Odette had carried out.

[37] She served as a technical advisor on a film on her fellow SOE agent Violette Szabo, Carve Her Name with Pride.

[36] On 23 February 2012, the Royal Mail released a postage stamp featuring Hallowes as part of its "Britons of Distinction" series.

[38] On 6 March 2020 Great Western Railway named a Class 800 train after her; the ceremony in Odette's honour was held at Paddington Station in London and attended by Anne, Princess Royal.