Cecily Mackworth was born on August 15, 1911, in Llantilio Pertholey, Wales. Although her mother moved to South West England after her father was killed in battle on the Western Front in 1914, Mackworth always considered herself Welsh.
Her aunt, Lady Rhondda, was instrumental in securing her a place at the London School of Economics for a two-year diploma in journalism in 1929. After this, Mackworth worked in Hungary and Germany and, after returning to London, married Belgian lawyer Léon Donckier de Donceel, moving to Brussels with him in 1935. They had a daughter Pascale Léonie Juliette in 1936.
After her husband’s death in 1938, Mackworth settled in Paris, entering the literary circle of Henry Miller (who published her poems in an offshoot of his magazine "The Booster") and Lawrence Durrell.
After WWII began, Mackworth worked with Rose Adler at her Books for the Army circulating library, and then became a Red Cross volunteer at the Gare d’Austerlitz.
In 1940, Mackworth escaped Nazi-occupied France; a journey that was recounted in her 1941 memoir "I Came Out of France". She remained in England throughout the rest of the war, working for the Free French, the Army Bureau of Current Affairs, and lecturing for Alliance Française. She also published "Czechoslovakia Fights Back", chronicling the resistance to the Nazi occupation, in 1942, and "Czechoslovakia" the following year.
Mackworth returned to France in 1946. She continued to write and published both "François Villon: A Study" and "A Mirror for French Poetry, 1840-1940" in 1947. Later that year, she was sent to Palestine as a newspaper correspondent and went again in 1949 to cover, as one of only two female reporters, the ending of the British Mandate. Her experiences there were shared in her book "The Mouth of the Sword".
She continued her real-life adventures in the 1954 book "The Destiny of Isabelle Eberhardt", in which she retraced the footsteps of Eberhardt across the Algerian Sahara. Mackworth also published two novels: "Spring’s Green Shadow" in 1952 and "Lucy’s Nose" in 1992, and her biography "Guillaume Apollinaire and the Cubist Life" received the Darmstadt Award in 1961. She went on to publish her own memoir "Ends of the World" in 1987.
She married her second husband, the Marquis de Chabannes La Palice, in 1956, and they stayed together, living in Normandy and Paris, until his death in 1980. Mackworth would be buried next to him in Normandy after her death in 2006, not long after finishing another memoir, "Out of the Black Mountains".