It is the absence of facts that frightens people: the gap you open, into which they pour their fears, fantasies, desires.

When I began to read as an adult, I read almost exclusively novelists of a generation back. I did the Russians, then I started getting more up to date. When you become published and become a reviewer, piles of books come along and you are pushed by fashion and what you are commissioned to do.

For me, it is about using everything that is there and using the gaps in the record, figuring out why the gaps might be there. And then when you move on to the level of what historians said, laying the interpretations side by side. You also have to look back at the documents and make your own judgments. What the record says and what people say about it. A novelist can fill the gaps in a way that a biographer cannot.

Rafe asks him, could the king's freedom be obtained, sir, with more economy of means? Less bloodshed? Look, he says: once you have exhausted the process of negotiation and compromise, one you have fixed on the destruction of an enemy, that destruction must be swift and it must be perfect. Before you even glance in his direction, you should have his name on a warrant, the ports blocked, his wife and friends bought, his heir under your protection, his money in your strong room and his dog running to your whistle. Before he wakes in the morning, you should have the axe in your hand.

I used to think that when I set out that doing the research was enough! But then the gaps would emerge that could only be filled by the imagination. And imagination only comes when you privilege the subconscious, when you make delay and procrastination work for you.

A novel should be a book of questions, not a book of answers.

Cravats grow higher, as if they mean to protect the throat. The highest cravats in public life will be worn by Citizen Antoine Saint-Just, of the National Convention and the Committee of Public Safety. In the dark and harrowing days of '94, an obscene feminine inversion will appear: a thin crimson ribbon, worn round a bare white neck.