Pincher's career as a journalist thereon mainly involved uncovering Cold War secrets in London for the "Daily Express". During his career, he had contacts within the British Government that suggested MI5 and MI6 could possibly be providing housing unwittingly for Soviet agents. Pincher always went "above and beyond" for his investigative reporting style, including checking people's personal phone calls and relentlessly importuning important people, such as Prime Minister Harold Wilson, for answers to questions that Pincher thought were being concealed from the public. He regularly provided exclusives that other journalists had missed, which led to his employers calling him "the lone wolf of Fleet Street". He made both friends and enemies in high places. In 1959, Prime Minister Harold Macmillan wrote to his Minister of Defence: "Can nothing be done to suppress or get rid of Chapman Pincher?" Pincher obtained the title "spy catcher" after he exposed several people as spies, one of the most famous being George Blake, an MI6 member who let close to one hundred Soviet spies get jobs at the embassy in London.