Analysis of information sources in references of the Wikipedia article "Secretary of state" in English language version.
At the Restoration [in 1660] the practice of appointing two Secretaries of State, which was well established before the Civil War, was resumed. Apart from the modifications which were made necessary by the occasional existence of a third secretaryship, the organisation of the secretariat underwent no fundamental change from that time until the reforms of 1782 which resulted in the emergence of the Home and Foreign departments. ... English domestic affairs remained the responsibility of both Secretaries throughout the period. In the field of foreign affairs there was a division into a Northern and a Southern Department, each of which was the responsibility of one Secretary. The distinction between the two departments emerged only gradually. It was not until after 1689 that their names passed into general currency. Nevertheless the division of foreign business itself can, in its broad outlines, be detected in the early years of the reign of Charles II. ... The first question to be considered in the light of the memorandum of 1684 is the origin of the office of Under Secretary. It should be emphasised in this connection that the term 'Under Secretary', although found in use as early as 1672, (fn. 28) passed only gradually into general currency.
