Isabel de Madariaga was born in Glasgow to Salvador de Madariaga, a Spanish diplomat, politician, and writer, and his Scottish wife Constance Archibald. As the daughter of a diplomat, she met many prominent figures of the 1920s and 1930s, including Maurice Ravel. She was educated in France and Switzerland, learning various languages, and then in Great Britain, where the family settled in 1936 after the outbreak of the Spanish civil war. She became the first female undergraduate at the School of Slavonic and East European Studies (SSEES) at the University of London, where she majored in Russian. After graduating with first-class honors in 1940, she helped monitor enemy broadcasts during World War II. In 1943, she married Leonard Schapiro, a lawyer and colleague in the monitoring services. In 1959, she completed a PhD degree on Anglo-Russian relations during the American War of Independence, with a dissertation later published as Britain, Russia and the Armed Neutrality of 1780 (1962). During her career, she became the most distinguished British historian of 18th-century Russia and helped transform the study of the subject as the author of classic works such as Russia in the Age of Catherine the Great (1981). She taught at the universities of Sussex and Lancaster before returning to the SSEES, where she became a professor of Russian Studies in 1982. She was named a fellow of the British Academy in 1990 and the Royal Spanish Academy of History in 1991.