Traditional studies (Wallace, 1975; Vital, 1968) of British foreign policy identified a central core of institutions involved in the policy making process consisting of the Prime Minister and the Cabinet, supplemented by the FCO and the Ministry of Defence (MOD). Surrounding this central core is what Vital identified as a ‘mantle’ of institutions which have an involvement in foreign policy but are not primarily responsible for it, such as the Department of Trade and Industry and the Treasuiy. Other departments only exercised influence through the machinery of the FCO. It is the FCO that bears direct responsibility for foreign policy, other organs of the British government being concerned with this topic only in the general supervisory sense, the foreign office does the work; they [other departments] approve or reject (Vital, 1968, pp. 49–50). This explanation of foreign policy making conforms to the realist paradigm of international relations. However, in the 1990s, Britain’s international commitments and membership in the European Union have transformed the foreign policy making system. This chapter will show that ‘domestic’ departments like MAFF and the EDG have extensive and important international responsibilities. The wide range of issues debated at the international level, and the proliferation of international organizations and regimes have drawn ‘domestic’ departments into the foreign policy arena. Reforms have been required in order to devote attention to international developments and to enhance the expertise of the ‘domestic’ departments with regard to changes in the international arena and the nature of international negotiations.