 They studied the role the Canadians were to play and assisted in the collation of the voluminous amounts of Intelligence detail, which poured into London from every conceivable source.This information was carefully sifted, examined, analyzed and, if corroborated by similar information provided by other recognized sources, was recorded and passed to the Operations Branch of the Planning Staff to consider what effect the data might have on the overall plan.The innumerable sources and agencies included refugees from Axis occupied countries, members of the various resistance groups, Allied personnel dropped by air into enemy held countries who then transmitted their information by portable wireless sets, raids conducted on the French coast for a specific purpose, air photographs, neutral newspapers, mail censorship, air reconnaissance, interception of enemy wireless radio broadcasts and countless others.