When I arrived at university, I knew – with all the unblinking certainty only an eighteen-year-old can muster – that I was a Tudor historian. Yes, I had more than a passing interest in the middle ages, but it was the Tudors who had fired my imagination ever since I was tiny. It didn't matter that I was hardly the first or last person to say that; what mattered was that I would seize every opportunity Cambridge offered to immerse myself in the world of the sixteenth century.

By the end of that year, all historical confidence had deserted me. My supervisors had taken apart everything I thought I knew about Tudor England, and I sat amid the debris, not sure of my next move. Taking a step forward chronologically was not an option, given that modern history, for me, was another country. Perhaps, then, I would look back, to the Wars of the Roses and beyond, even if it meant encountering the formidable supervisor of whom historians from my college spoke in hushed, sometimes quaking tones.

What happened next changed my life. It sounds like an exaggeration, I realise. But what Christine opened up for me was a different historical world. She required forensic thought about the deepest structures of politics, as mercilessly revealed in medieval society by the absence of the institutional apparatus the modern world takes for granted. Why did anyone obey a medieval ruler; how could anyone even know what he (it was almost but not quite always a he) commanded, given the startling absence of a standing army or a police force, let alone modern forms of transport or communication? These were questions – extraordinarily, it now seemed – that I had never been asked before. And it immediately became clear that thinking about power in these rawest and broadest of terms necessitated thinking about people; about principles and pragmatism, about political, theological and literary culture, about the complex intersection between self-interest and perceptions of the common good, about the role of individual human beings within wider forces of social change. It was fascinating, and it made the past vividly real, in three demanding dimensions.

Not only that, but for the first time I began to feel I was being equipped with the tools to construct my own responses. The process could be terrifying: Christine's standards of thought, analysis and expression are unyielding.