In my struggle to see and hear what I was writing, I used whatever came to hand. I overheard Alice and her friend Ellie on the back steps after school one day having a spitting competition. I didn’t take notes or plan to use that—but the next day I found myself writing a scene in which Wiseman, as a child, had a spitting competition with his sweetheart Sophia. It made a nice warm moment between them.

I spent a couple of nights in the public ward of a hospital and made a note on a paper towel about one of the other women in the room: ‘Old Mrs Priestley—her cough the only strong thing about her.’ When I got home and found the paper towel in my handbag, I gave that cough to Wiseman’s mother. Then I realised that the cough meant she had TB, and that she’d died when Wiseman was barely more than a child.

It helped to smell as well as to see and hear. In the early documents I’d kept coming across references to something called a ‘slush lamp’. What was it made of? What did you burn in it? What sort of light did it give?

A good child of the modern age, I Googled ‘slush lamp’ and to my surprise found several sites that told me it was a small dish full of fat, with a wick that hung into the fat and over the edge.

That night I cooked lamb chops for the family dinner, catching the fat in the griller. This I poured into a little dish. Then I cast about for a wick. Cotton, not too thick. A narrow strip of rag might do. I draped this into the fat, lit a match— flint and steel would have to wait for another day—and stood back.

In the next thirty seconds I learned more about life in a bark hut on the Hawkesbury in 1817 than all the books in the world could have told me. The slush lamp produced vast amounts of dense black smoke, which smelled powerfully of burned fat.

The flame was tiny, hardly making a dent in the darkness. Watching the fat burn away I realised that those settlers had had a choice: a scrape of dripping on their dry bread, or light at night. They couldn’t afford both.

I went back to the desk and rewrote all the scenes in the hut at night.

I enjoyed making the slush lamp and I went through the draft, looking for other things I could try out. I travelled in a small boat along the Hawkesbury, made and ate ‘hominy’ and ‘pease’, had a go at making fire from two sticks (I couldn’t even get them warm) and did a thousand other small experiments.