I went to the Mathematical Institute a couple of days later and was given a desk in the visitors’ office, an e-mail account and a swipe card for getting into the library out of hours. There was only one other occupant of the office, a Russian called Podorov, and we exchanged brief greetings. He paced up and down the room, slouching, and occasionally leaned over his desk to scribble a formula in a large hardback notebook that looked like a book of psalms. Every half hour he went out and smoked a cigarette in the little paved courtyard outside the window.

Early the following week I had my first meeting with Emily Bronson, a tiny woman with very straight white hair, held back with hair clips like a schoolgirl’s. She rode to the Institute on a bicycle that was too big for her, with a basket for her books and packed lunch. She looked a little like a nun, and seemed shy, but in time I found that she had a razor-sharp sense of humour. Despite her modesty I think she was flattered that I had called my thesis ‘Bronson’s Spaces’. At our first meeting she gave me copies of her last two papers, and a handful of brochures and maps of places to visit in Oxford before, she said, the new term began and I had less free time. She asked if there was anything in particular I missed about life in Buenos Aires and when I hinted that I’d like to take up tennis again she assured me, with a smile that showed she was accustomed to far more eccentric requests, that it would be easy to arrange.