Professor Ashton studied for his undergraduate degree at Christ's College, Cambridge, where he continued on to gain his PhD. On completion of his doctorate he obtained a Temporary Lectureship at Salford University, before moving on to a permanent Lectureship at the University of Liverpool. Professor Ashton moved to the LSE in 1998.
Professor Ashton's main fields of interest are contemporary Anglo-American relations and the modern history of the Middle East. These interests came together in his first book, Eisenhower, Macmillan and the Problem of Nasser: Anglo-American Relations and Arab Nationalism, 1955-59 (Macmillan, 1996), which looked at the strategies adopted by Britain and the United States to deal with the Arab nationalist challenge during the 1950s. His second book, Kennedy, Macmillan and the Cold War: the Irony of Interdependence (Palgrave, 2002), broadened the frame of reference to look at Anglo-American relations over a whole range of international issues during the Kennedy Presidency. Kennedy, Macmillan and the Cold War was awarded the Cambridge Donner Book Prize for 2003. This prize rewards excellence in advancing scholarly understanding of transatlantic relations.
In September 2008, his most recent book King Hussein of Jordan: A Political Life was published by Yale University Press. Based on unique and unprecedented access to the private papers of the late King this book provides a comprehensive analysis Hussein's statecraft, including his role in the Middle East peace process, the Arab-Israeli wars of 1967 and 1973, the Iran-Iraq war, the Gulf crisis and the campaign to unseat Saddam Hussein in the 1990s. It also illuminates the personality of one of the most colourful and charismatic Arab leaders of the twentieth century.