British Empire:

After the German occupation of France in 1940, Britain and the empire stood alone against Germany, until the entry of the Soviet Union to the war in 1941. British Prime Minister Winston Churchill successfully lobbied President Franklin D. Roosevelt for military aid from the United States, but Roosevelt was not yet ready to ask Congress to commit the country to war. In August 1941, Churchill and Roosevelt met and signed the Atlantic Charter, which included the statement that "the rights of all peoples to choose the form of government under which they live" should be respected. This wording was ambiguous as to whether it referred to European countries invaded by Germany, or the peoples colonised by European nations, and would later be interpreted differently by the British, Americans, and nationalist movements.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". Which British Prime Minister signed the Atlantic Charter?
Churchill