Within the policy rationale of a "self-improving" school system, there are now several thousand National College designated "system leaders" working as consultants in English schools on aspects of school to school support. So far, there has been no systematic consideration of the long-term development of these consultants in ways that are consonant with values and concerns of education professionals. This article addresses this challenge by presenting an agenda for consultancy development in English schools which will also have wider relevance for the international community. Six areas of enquiry and propositions for action are identified and the principles and practicalities of implementing them in a school-led system examined. Conclusions are drawn about the importance of being proactive in setting a long-term agenda for "system leader" consultancy development in schools that is historically grounded in democratic process and notions of public value.