Five-minute Memoir: Hannah Rothschild recalls her influential great-aunt

My great aunt Miriam was born in 1908 and devoted her long life to the study of insects and the protection of animals and underdogs. My first memorable encounter with her happened when I was about eight. One winter evening the doorbell rang. My parents were giving a formal dinner downstairs and, like my siblings, I should have been in bed on the nursery floor. Hail disobedience. Leaning over the banisters I saw Great Aunt Miriam standing in the hallway holding a large box covered in a cloth.

"Miriam, hello, we weren't expecting you." My father's voice betrayed surprise and slight nervousness.

"I've got something to show the children," she said in her imperious way and made her way to the dining room. I shot after her. To the astonishment of the assembled dinner guests, Miriam, without introducing herself, sat in my father's chair and beckoned to me to come closer. Placing the box on the table, she swept away the cloth revealing a box whose sides were made of a fine silver mesh. At first all I could see was a desultory collection of twigs. Then some of the shoots began to wriggle.

"Caterpillars!" I whispered. Miriam moved a candlestick closer and in the flickering light the larvae were transformed into iridescent flashes.

"I've been feeding half of them on marijuana and the rest on cabbage to see if their diet affects the biochemistry of insect communication," she explained. "An unexpected side effect has been that some caterpillars have changed colour. But I haven't worked out why yet."

It was one of the first lessons Miriam taught me; embrace the unexpected with gusto, in life as well as in science.

"One of the reasons women fail to get far in life," she'd lecture me, "is that they spend far too much time on their appearance. Choose one style of dress and one haircut and you might get somewhere." Her hair was long but neatly clipped into a chignon and covered in a scarf made from the same material as her rather shapeless dresses.

Going to visit Miriam, my spirits would quicken as I drove through her local village and up the raggedy lane to Ashton Wold, the house where she lived amid fields teaming with deer and the wildflower meadows that she has became so famous for promoting. In an attempt to save money on heating, Miriam sliced off the whole top floor, thus lowering the once-imposing three-story façade. But few could really detect the "bones" of the property thanks to her decision to let a riot of ivies, roses, honeysuckles, wisteria grow all over it, unchecked. At the height of summer Ashton Wold looked more like a buzzing rustling mound of greenery than a house.

This place is Liberty Hall – do whatever you like here" she was fond of telling guests who included visiting professors, the odd duchess, Isaiah Berlin, John Sparrow and an assortment of acquaintances who she had met on her various travels. Tea was set out permanently on a long table in the drawing room so that anyone, including the house's enormous population of mice, could help themselves. Lunch was always served with a minor Rothschild wine and the table was laid for at least 10 lest any unexpected visitors appeared.

When I broke the news that I was making a film and writing a book about her rebellious youngest sister, Nica, Miriam was cross. Though she loved Nica, she thought her "vulgar" and somewhat irresponsible. While Miriam had stayed at home and continued her father's work, Nica's passion for New York's jazz scene and the music of Thelonious Monk had driven her to leave Europe. I suspect Miriam also wondered, as did others, why I wasn't writing about her. She was also livid when she discovered how little I knew about our Rothschild forebears. "I was never terribly interested," I confessed.

"Not interested! Are you aware that a person's life is shaped long before they are born?" she said, glaring at me. "Why are you doing this, Hannah? Is it just about self-publicity?"

"There are many easier ways to get publicity," I answered defensively.

"Why does it have to be about family?"

"You wrote about your uncle Walter."

"That was different. It was about science, and science matters."

"Music matters to many."

But Miriam was not entertaining that.

"Shall I stop coming?" I asked.

"Oh I suppose you'd better not."

If I did not visit for a while, she would telephone. "When are you coming? I'll be dead soon." Then she would hang up. I miss her dreadfully.

'The Baroness' by Hannah Rothschild is published by Virago on 3 May