Thomas Tallis history department have an interesting approach to planning. Whereas, all too often, this most time-consuming and intellectually demanding of teachers’ tasks is rendered invisible, and is supposed to happen by magic in the middle of the night, this department chose to make the planning process genuinely collaborative, pivotal in securing quality, and a priority for time and resource allocation in its ‘Development Plan’. This is a department that took two big ideas very seriously: first, the history curriculum idea of an enquiry or ‘big question’, and, second, the professional development idea of peer review. If an ‘enquiry question’ is used to drive pupils’ motivation across a lesson sequence, and if it is constantly explored with pupils as a focus for their historical thinking, then its wording becomes highly significant for teaching and learning, rather than just a heading on a workscheme. Inspired by Michael Riley’s rationale for such questions (May 2000, Teaching History 99), Thomas Tallis history department created a framework within which rigorous lesson objectives and purposeful learning activities could be constructed. All members of the department (including the head of department) submitted their work to the rest of the team for scrutiny against agreed criteria. The Thomas Tallis concept of peer review gives a new status to medium and long-term planning – making a valued and satisfying professional development experience out of an essential, time-consuming and reflective task.