Walter Hines Page bleg

What is the best source detailing the activities of Walter Hines Page (President Wilson’s Ambassador to the Court of St. James) in advising the British government about how to conduct propaganda operations in the United States, prior to U.S. entry into World War I?

How about for the general American view (during the 1920s) that American entry into WWI was a mistake, and the U.S. had been tricked by British business interests?