Chapter 5 explores the politically appointed staffs working in ministers’ and prime ministers’ offices. Comparative analysis showcases the flexibility of policy advisory systems (PAS) and the several interpretations of the Westminster tradition. Advisers were added to PAS to extend ministers’ control, address deficiencies in public service advice and increase ministers’ capacity to address the politics of policy work. Their effects have attracted debates about politicisation. At best, advisers identify political risks and help ministers avoid the derailment of policy agendas.They serve as ports of call for officials, interested stakeholders and other ministers, as well as facilitate the circulation of policy advice within government. At worst they have corrosive effects, overstepping boundaries by throwing their weight around and directing public servants without appropriate authority. They act as gatekeepers on the professional advice of the public service before it reaches ministers. There is widespread agreement that partisan advisers have become more prominent and influential. Central political offices have become adept at using them as systemic instruments to secure political alignment and coordination throughout government. Their growing numbers and the specialisation of policy functions have become important for how ministers exert political control and seek contestable policy.

The examination of Westminster policy advisory systems begins with the administrative tradition that has fundamentally shaped, and continues to influence, the practices in the four cases and the country-specific developments. The anglophone countries constitute a coherent set because of their common tradition and their close historical and ongoing associations and interactions. This overview addresses the shared characteristics of the Westminster-type system and the constituent features of government pertinent to policy advisory systems. It compares public organisation and structures and unique characteristics, focusing on political executives, the machinery of government and ancillary public sector advisory agents (e.g. parliamentary committees, commissions of inquiry). The unique characteristics of the cases are examined, such as the distinct patterns of public sector reform that have implications for policy advice and the role of central agencies vis-à-vis departments.