"We didn't know anything about her or even see any pictures of her growing up; our father was so secretive about his past. But the old family friends who greeted me on my first trip to Israel were struck by how like Yolande I looked, although it would be years before I understood what she actually did for the country," she explains at her Kensington home.
It was lifelong rage at the lack of recognition for her invaluable intelligence contribution which inspired Gilbert - Miel and Alain's father and Yolande's only son - to make a film made about her life. Although Miel, 47, could not spare time away from raising her two children to travel to Egypt and participate in filming, she lent her creative ideas for visuals and music as well as production finance for the documentary. It takes the viewer from Paris, where Yolande was educated, to Cairo, where she perfected her espionage techniques, to Jerusalem, where she delivered her secrets, and back many times over.
Born in 1913 in Alexandria and educated in St Germain-en-Laye, Yolande got the de Botton name from her first husband, a Cairo cotton dealer she divorced when Gilbert was three. He barely knew her, he confessed, until moving to Cairo to live with her after spending his earliest years with his grandparents in Alexandria.
It was her beauty, courage and readiness to deceive that made an activist out of Yolande according to Ora Schweitzer, her assistant at the Jewish Telegraphic Society in Cairo, the cover for their intelligence-gathering organisation. "She was very bright, but she knew how to play the dumb blonde, and the husband of an activist friend got her involved," says Schweitzer, who remembers her transferring important information to Jerusalem as early as 1942.
Too young to know what was going on, Gilbert did learn at first-hand that his wild young mother had a lust for danger. "She used to take me sailing in a dinghy in Alexandria harbour and laugh as I ducked just before we looked set to hit the rocks," he remembers. Back in Cairo, Yolande famously risked arrest by loudly importuning King Farouk in the restaurant of the legendary Shepheard's Hotel, asking for the interview his aides had ignored all requests for. Charmed, Farouk handed the blonde his card.
In 1945, Yolande was put in charge of recruiting a network of Egyptian agents that included members of the Muslim Brotherhood. Ben Gurion visited her in Cairo in 1946, and in 1948 she flew to Palestine to pass him secret plans for Syria and Egypt to invade the new young country, which she had sewn into her shoulder-pads. He sent an armoured car to pick her up with her secret papers, but could not dissaude her from flying back to Cairo, where her life would clearly be in danger.
It is less surprising that she was outed by members of the Brotherhood, arrested and jailed in 1948 than that she lived to continue her clandestine activities for several more years. Released months later after falling so ill she was unable to walk, she left for France, but soon became active in Israel's UN delegation.
And the charm worked for her all over again: "The Arab delegation treated her more like one of them than someone from the other side," says de Botton. "They believed in her sincere affection for them."
Yolande insisted on returning one last time to Egypt, where she was readmitted to high political circles before finally admitting in 1951 that her number there was up. With Gilbert, she settled in Israel, where he remembers their "Robinson Crusoe existence" in a tiny flat lined with valuable carpets bigger than the rooms themselves. Yet she never yearned for the glamorous life she might have lived in Cairo, Alexandria or Paris.
Only two things upset Yolande - the death of the love of her life, the airman she married in the 1940s, whose name - Harmor - she kept to the end of her days. The second was her rejection by an Israeli government who considered her irrelevant and too exotic by far, and marginalised her with a desk job in Protocol.
"She was dove-ish and her elegance was considered a sign of decadence," mourned Gilbert, who saw her for the last time in 1954, when he left for a university education in the US. But he used the wealth he amassed as the founder of Global Asset Management to name a square after her in Jerusalem and lay a plaque in the cemetery where she is buried.
