This study describes the British government’s policy towards China during the first phases of the undeclared Sino-Japanese war, starting in July 1937 and ending in September 1939 when the outbreak of the war over Poland forced the British government to turn almost all its attention to Europe. The dilemmas confronting British policy-makers in the Far East are analysed together with the implementation of their subsequent solutions. Attention is focused on the question of British interests in China and on the decisive factors and considerations which determined British policy and Britain’s role in the Sino-Japanese war.