There were 25 Principal Private Secretaries (PPSs) to the Prime Minister between John Martin in 1945 and Chris Martin in 2015, and 27 foreign affairs Private Secretaries (PSs). This chapter examines the job and incumbents of the PPS position, before turning to the position of the foreign affairs PS, and concludes by looking at the factors that explain why some foreign affairs PSs have been far more influential on the formation of policy than even the Foreign Secretary, while others have been comparatively modest figures. The PPS and the foreign affairs PS were then relocated to a larger oblong room through more double doors on the opposite side to the Cabinet Room. Five phases can be discerned in the evolution of the foreign affairs PS position are restrained foreign affairs PSs, heavyweight foreign affairs PSs, Return to normality, the foreign affairs PS under the Joint Number 10 and National Security Council.