Yale Library now offers access to the database Confidential Print: North America.
"The Confidential Print series issued by the Foreign and Colonial Offices since c1820...originated out of a need for the Government to preserve all of the most important papers generated by the Foreign and Colonial Offices. Some of these were one page letters or telegrams – others were large volumes or texts of treaties. All items marked ‘Confidential Print’ were printed and circulated immediately to leading officials in the Foreign Office, to the Cabinet, and to Heads of British missions abroad." Read more, and search or browse the database.