This research aims to identify the extent of the influence of the Ofsted inspection regime on how headteachers lead their school. Data was gathered from questionnaires, interviews, school and Ofsted documents and the 28 participants were all headteachers at secondary schools. As a fellow serving secondary school headteacher and a part-time Ofsted inspector, this has given me a unique insight although the ethical challenges are carefully considered. The report concludes that the Ofsted inspection regime has shaped the way the headteachers think about how their schools are run, particularly through the lens of accountability. This has led to an almost unquestioning acceptance that the ideal model for teaching and learning comes from Ofsted. The inspection provider then assesses how well schools meet it, punishing them heavily for student outcomes that fall below national measures of success. Headteachers have stopped thinking about how it might be different in their context and are sleepwalking into a performativity culture so that their schools are seen as being successful at an Ofsted inspection. They have accepted the surveillance strategies used by Ofsted along with the disciplinary power wielded when the Ofsted model is not met. However, the most fundamental tension surrounds vocational qualifications: how they are used in the national performance tables and then by Ofsted in their inspections. Headteachers are doing what it takes to 'survive' and 'thrive' in the market approach to accountability that schools find themselves in. Although this report has implications for policy makers, headteachers and Ofsted, it concludes that this area is worthy of further investigation, particularly into how the ideal teaching standard is arrived at along with an exploration of appropriate measures of school performance used by Ofsted.