北伐時期是中國現代史上的重要階段，軍事的推演、政治的發展、社會的變遷無不有令人矚目的鉅變。但如果不了解這時期錯綜複雜的外交關係，依然無法掌握整個時代的變貌。對當時的中國人來說: 「全球之帝國主義不單是英國，惟英國可算是帝國主義之巨魁了。」英國是中國人反帝國主義運動的主要對象，她在華扮演的角色可說相當特殊。過去學術界有關這一時期中英關係的論著不是沒有，但以 1927 年英國在上海增兵一事件為論述主題的，尚不多見。 本文的目的即是希望透過英國國家檔案館 (Public Record Ofice，Kew)的豐富外交史料．以這一事件作為引子，敘述過去鮮為人注意的歷史事實，並由此勾勒出北伐時期英國對華外交發展的軌跡。

　　　　　The Northern Expedition spans a decisive period in modern Chinese history, characterized by military changes, political developments and social transformations. However, without understanding this period's intricate foreign relations, it is not possible to have a solid grasp of this complicated but exciting era. During this period, many Chinese believed that "although Britain is not the only imperialist nation in the world, it is the most powerful one." Being the primary target of Chinese anti-imperialism, Britain played a special role in China. There is no lack of academic works on Sino-British relations, but no scholar has yet attempted to examine the 1927 incident, when Britain militarily reinforced Shanghai, in full length. This paper uses the rich archival materials of Britain's Public Records Office to shed light on the incident, highlighting some of its neglected dimensions and providing insights into Britain's policy during the Northern Expedition.