This article examines the role of the consultants in secondary schools and local authorities within a large-scale consultancy-based reform, the Secondary National Strategy (SNS), in London, UK. The SNS follows a cascade model of implementation in which nationally created initiatives are introduced and supported within local authorities (LA) and schools through LA-based consultant teams. The article is drawn from a larger interpretive case study that follows the experiences of SNS consultants working within the reform from 2002 to 2006. The article uses semi-structured interviews to reveal the various and diverse experiences that occur in schools as a result of the introduction of consultants within LAs. The article argues that introducing an SNS consultancy structure to work within LAs and secondary schools created dynamic, complex and shifting effects across secondary schools. While consultants often attempted to create developmental or learning experiences that resonated with teachers' and departments' experiences, these activities may also have served to further the institutional control of teachers' workspaces. These effects are part of the complexities that exist within school change agendas. Exploring these contradictions helps in understanding school change within urban secondary schools. (Contains 2 figures.)