The heart of the Restoration regime's intelligence system from 1660 to 1685 lay within the office of the Secretaries of State. In particular from 1662 to 1674 the most significant work in this area was undertaken within the office of Sir Henry Bennet, Earl of Arlington, where the control of intelligence fell to Sir Joseph Williamson. In a period of great turmoil the Secretary of State's office concerned itself with the Stuart regime's security. Many of the precedents taken from the former republican regimes were re-established under Williamson's control and in turn they passed to his successors in the secretaryship, the Earl of Sunderland, Sir Leoline Jenkins and Charles Middleton. In the context of the threats which faced the regime intelligence and espionage work was an important area for the secretariat as we shall see. As the office developed, the general trend was for increasing centralisation and the creation of a government system of intelligence and espionage activities.

The development of the office of Secretary of State within the administration surrounding the monarch was a slow process. The office emerged from the shadow of the post of personal secretary to the king, but by the mid seventeenth century it had become established as a high office of state; although in political terms it still fluctuated in power. To a great degree it was the man who made the office rather than the office the man. The secretaryship undoubtedly found difficulty in divorcing itself from its roots and its relationship to the monarch was both its potential strength and its weakness.