From 1959 to 1961 she was Consul and First Secretary to Léopoldville, which in practice meant being head of MI6 there. British parliamentarian David Lea wrote that shortly before she died, she claimed to have been involved organising the abduction and murder of Patrice Lumumba during the Congo Crisis. Park (allegedly) confided to Lea that the reasoning behind the assassination was MI6 fears that Lumumba would hand over the high-value Katangese uranium (Shinkolobwe) deposits as well as the diamonds and other important minerals largely located in the secessionist eastern state of Katanga to the Russians. The Shinkolobwe uranium mine provided the uranium used by the Manhattan Project, including in atomic bombs dropped on the Japanese cities of Hiroshima and Nagasaki in 1945. She rose further through the ranks of the Foreign Office to serve in the British High Commission in Lusaka from 1964 to 1967 and then Consul-General to Hanoi from 1969 to 1970. In 1972 she was Chargé d'Affaires of the British Embassy of Ulan Bator for several months. From 1973 onwards she served in the Foreign Office then retired two years early in 1979 to become Principal of Somerville College, Oxford.