Recent years have witnessed increasing interest amongst international historians on the influence by experts on foreign policy decision-making. Most work thus far has concentrated on American foreign policy since 1945, but this analysis broadens the focus to consider the impact of experts on British decision-makers through the use of informal networks below the level of Cabinet ministers whilst debating the future of the city of Danzig at the Paris Peace Conference of 1919. It shows that despite a tendency by the protagonists to interpret their actions as subverting the official role and function of the Foreign Office, sufficient evidence can be found to suggest that through the use of back-channels to David Lloyd George, the prime minister, via Philip Kerr, his private secretary, some officials, such as James Headlam-Morley, within the Office managed to influence high-level decision-making at Paris. Whilst experts must be seen as acting alongside professional diplomats, rather than marginalising them, a focus on the subject helps explain different approaches taken by participants at the Conference, and why senior figures such as Sir Eyre Crowe came to approve their intervention in the dispute over Danzig. It also allows a new view to be taken of why the compromise decision was taken, despite the guiding principles laid down by the peacemakers in the year before the Conference opened. 2 Among all the territorial problems dealt with at Paris none was more difficult than that of Danzig. .. . This question was the cause of acute differences of opinion within the British delegation itself, and was debated with great persistency between the Allies during the four months which preceded the settlement. The decision eventually arrived at was essentially a British one; it was suggested by members of the British delegation and carried through by the Prime Minister in the face of much opposition. Headlam-Morley, April 1925 2 Writing in April 1915, Lewis Namier, recently demobbed from the 20 th Royal Fusiliers owing to his poor eyesight, warned that "Pharisaic doctrine is almost as dangerous as the mongerer in 'political geography'". 3 His warning was apposite, as the Great War was in the process of destroying the established order of multinational empires in Central and Eastern Europe. The question that confronted statesmen was: what would replace them? There was little agreement, save for the principle of national self-determination of peoples as a way to prevent a future war, when the present conflict was at least in part caused by the divisive force of frustrated nationalism. This concept, however, was far from a panacea to solve all of Europe's problems. In applying the principle of "political self-determination" in the disputed areas of the continent, Namier suggested, "perhaps we should be guided by instinct rather than strict logic". In these short lines, the future prominent historian of eighteenth century England outlined the key issue facing the peacemakers: the almost impossible task of matching a peace based on ...