Mary Katherine Herbert was born in Ireland on 1 October 1903.
At the outbreak of the Second World War, Mary worked in the British Embassy in Warsaw, then as a civilian translator in the Air Ministry. She joined the WAAF on 19 September 1941 and, at her own request, transferred to the SOE in May 1942, aged thirty-nine.
A well educated woman with a degree in art, Mary was fluent in French, German, Italian and Spanish. She also obtained a diploma from the University of Cairo in Arabic.
Mary trained with Lise de Baissac, a contact who later would have a significant influence on her life.
Mary arrived in France on 30 October 1942. She travelled to Bordeaux
to act as a courier for the Scientist circuit, using the codename Claudine. In keeping with fellow SOE agents she travelled by bicycle and train, liaised with the French Resistance, carried messages, sought safe houses and potential recruits. Another task familiar to Mary and her fellow agents was to arrange and attend parachute drops as fresh agents arrived in France.
In France, Mary caught up with Lise de Baissac. She also met Lise’s brother, Claude. An affair between Mary and Claude produced a daughter, Claudine, born in December 1943. After the birth, Mary and Claudine moved into a flat maintained by Lise.
On 18 February 1944, the Gestapo raided Lise’s flat and arrested Mary in the belief that she was Lise. Separated from her baby daughter, Mary remained in prison until Easter 1944. During that time she created a cover story for herself stating that she was Madame Marie Louise Vernier, a Frenchwoman from Egypt. Despite interrogation by the Gestapo, Mary did not waver from her cover story.
Upon her release, Mary hid in a small country house near Poitiers. In September 1944, after a difficult search conducted in trying times, she was reunited with Claude and Lise.
Mary married Claude in November 1944. After the war, she lived a quieter life giving private French lessons.
Mary died on 23 January 1983 with her daughter Claudine at her side.