This thesis is an analysis of British foreign policy regarding Norway between September 1939 and April 1940. Its focus is on how the British Government adjusted its policy towards Norway’s neutrality, from an attitude of respect to the final decision to break Norwegian neutrality was made. More specifically, the thesis recognizes the most important internal and external factors and investigates how they influenced the Chamberlain Government’s attitude towards Norway, and measures and compares the amount of pressure these factors had on British policy makers. Norway’s vast and neutral coastline emerged as one of the biggest problems for British war considerations during the period of this study, due to the German transport of iron ore, and the investigated factors represented different varieties of pressure on the British Government to do something about this growing issue.