I’m reading through twenty-six years of weekly letters from Katharine Susannah to her son, Ric Throssell. There’s thousands of pages of handwriting to decipher, and if I did nothing else for a whole day’s work, it would take two days to get through one year. I have made it from 1943 to the end of 1947 in the first few weeks of the endeavour. With so much of her correspondence lost or destroyed, these letters are Katharine at her most revealing.

I photographed as many of them as I could in my research trip to Canberra in October. It was a numbing task, photographing page after page, and I got careless: so many are out of focus, and I berate my earlier self for arbitrarily blurring out pages of the past.

I’m reading the letters for clues to her earlier self, as my focus is on the years 1883-1919, and she is writing decades after this. I’m constantly side-tracked, drawn into the dramas of her present; there always seems to be something interesting happening. How much can we learn about a person’s youth from their personality at sixty? For example, are the introverted elements of Katharine in these letters – as she complains about having to attend a party or make small talk at a luncheon – true of her younger self? How differently did she see the world after the second suicide in her life, that of her husband in 1933? Is there a chasm between the Katharine before and after this event?

There are mentions of people she knew in her youth and family members, and events in her days as a journalist in London. I seize on these, but they are just morsels. I learn that she used to play cribbage with her father. That one of her parents’ wedding presents was a set of coffee cups with “queer Irish figures chasing round them”, and it was a “great, great treat” – or at least consolation – to be able to drink from them when forced to take a dose of castor oil. And then there’s Billy Pill – or is it Billy Pitt? (her handwriting is notoriously difficult) – who shows up at her door in 1946, talking of the old days when he proposed to her on the boat. He makes the mistake of saying politics doesn’t matter to him, and even though he tries reading one of her pamphlets, she regards him as someone she wants as no more than a “casual acquaintance”. Morsels I hope will add up to a fuller picture of Katharine.

It feels at times that I’m only getting one side of her personality, that of “mother” – albeit a significant one. When this is the self I have best access to, it’s easy to make it the defining self. But I’m certain she was a different person to friends, comrades, other writers. All biographies are shaped by what has survived, and some selves survive better than others.

I’m lulled into a sense of intimacy with Katharine, as if I’m an invited party to her letters. Then I find her mentioning “I don’t ever want any strangers to be delving into those old notebooks & rough scripts”, and I realise I am the stranger. I’m not looking at the forbidden notebooks or drafts; she burned those. But I wish I could. One of them, she says, dates to when she was twelve. I feel sad thinking about that notebook going up in flames; the tragedy of the archival conflagration hits harder when it becomes specific. I’m going to be writing about twelve year-old Katharine soon, piecing together the fragments I can find, with nothing as substantial as that notebook.

I could spend so long mourning what is lost, but I should be celebrating what has survived. I am so grateful to the late Ric Throssell for giving such a literary gift to posterity by preserving these letters and allowing scholars access to them. Reading through them is a privilege, a strange journey I’m undertaking with Katharine, knowing some of what lies ahead of her already, and hopefully learning some more of where she’s come from.