Odette Marie Celine Brailly was born in Amiens in the Somme département of France. She married the English subject Roy Sansom in 1931, moving with him to England. When the War Office requested all French-born residents of London to supply them with photographs of their home towns, Odette volunteered her family album which contained many useful depictions of the Channel coast. She was asked to train under Colonel Maurice Buckmaster of the Special Operations Executive and return to France to work with the French underground in Nazi-occupied France. She left her three daughters in the care of her husband.
Churchill's operation in France was betrayed by a double agent, and Odette and Churchill were imprisoned. Under torture by the Gestapo at Fresnes prison in Paris, Odette stuck to her cover story that Churchill was the nephew of Prime Minister Winston Churchill, and that she was Peter's wife. The hope was that in this way their treatment would be mitigated.
Odette's husband had died during her imprisonment and she married Peter Churchill in 1947. They were divorced in 1956.
Her third husband was Geoffrey Hallowes.