This research explored the extent to which secondary school history teachers in England willingly engaged with a series of concurrent curriculum reforms, and the factors that shaped their level of agency in the process. The curriculum has been the target of sustained reform by many governments, and accountability measures are frequently used to compel teachers to engage with the process of change, as teachers are often seen as resistant to change. Data were obtained through online surveys conducted annually from 2015 to 2017, providing a large, longitudinal data set of over 1100 individual responses. Responses to closed items were analysed using SPSS to generate descriptive and inferential statistics, and qualitative responses were coded to identify key themes. Generally the teachers were reluctant to engage in the process of reform. There was some statistically significant variation between teachers in different types of school. Teachers' willingness to engage with changes was also related to their sense of subject identity. However it is evident that accountability measures dominates teachers' thinking, and even impacts on what teachers choose to do in non-examined phases of the curriculum. This appears to diminish teachers' agency when creating a curriculum.