The Pilgrims Society was a semi-official public diplomacy actor in the field of foreign relations and a trailblazer for organisations like the British Council and the Division of Cultural Relations, which themselves were precursors to Cold War organisations like the United States Information Agency. The history of the Pilgrims Society tells of a gradual shift from unofficial actors providing the main impetus in public diplomacy to official actors providing the main impetus. The Society contributed to this shift by its support and facilitation of Earl Grey's cultural diplomacy in 1906; through its propaganda, advocacy, and exchange diplomacy during the First World War; and by means of the increasing use of the Society as a venue for policy announcements and advocacy diplomacy by US ambassadors in the 1920s and 1930s, and again in the critical year of 1941.

The Society's decreased relevance in more recent years was to a degree caused by the increased part played by the state in public diplomacy and propaganda roles. This was a development that the Pilgrims contributed to in the first half of the twentieth century. As such, the Pilgrims Society confounded early twentieth-century definitions of ‘public diplomacy’ as ‘open diplomacy’. Firstly, the Pilgrims’ involvement in foreign and international relations was by no means ‘open’. The Pilgrims represented an exclusive network of elites, closed to democratic accountability or popular involvement. For the entirety of the period covered by this book, the Society excluded people on the basis of class, gender, and race. At the same time, it sought to influence official and unofficial relations between the two polities in which it operated. Secondly, and more importantly, the Pilgrims acted primarily in the realms of advocacy and cultural diplomacy in an attempt to influence foreign and international relations by engaging with foreign publics. These actions characterise public diplomacy as it is understood today and, indeed, helped formulate that characterisation. The Society was able to do this via its status as an elite club rooted in the associational culture of London and New York.