As she moved up and down the hall and past his desk, my friend’s thoughts, despite his best efforts, kept turning to the presence of this good-looking, sensual woman.

Not something you want to happen when the occasion calls for close attention to the causes of the First World War.

She was indeed attractive, right up to her death at the age of 68.

Not just physically but in her personality and character, too. In Are You Somebody? the memoir that made her famous, she wrote about herself and her family. Nothing was ducked or avoided.

Her parents’ unhappy marriage, her mother’s alcoholism, her own sexual encounters as a teenager and as a young woman in Dublin during the Sixties.

She wasn’t boasting about her experience but she wasn’t apologising for it either.

She simply wrote about it, wondering at the pain and pleasure of things then.

Writing about family and adolescence and early adulthood is a common activity among Irish writers — I’ve done it myself. What made O’Faolain’s book absorbing and an international bestseller was its honesty. How could she reveal these things about herself and others?

O’Faolain said she wrote it to make sense of her life to that point, never thinking that it would be of interest to others or find its way into print. But it was, and it did, selling hundreds of thousands of copies.

She was a TV producer with the BBC and RTE, and a columnist for the Irish Times and, at the time of her death, for the Sunday Tribune, for whom she was providing coverage of the US presidential primaries.

When she was diagnosed as having terminal cancer, she returned to Ireland and contacted RTE. Then just four weeks ago she did an interview with her friend, the RTE radio presenter Marian Finucane.

In it she described in detail the diagnosis of her illness and her feelings in the face of approaching death.

I have never heard an interview as moving or as frightening. O’Faolain is not the first sufferer from cancer to discuss her disease, but the way in which she laid out her loneliness and fear for all to hear was, paradoxically, immensely courageous. She felt alone, she said.

She felt in despair, not just because she was terminally ill, but because that knowledge had almost immediately drained life of its sweetness — ‘soured life’, as she put it.

The things that had given her pleasure, like reading, meant nothing any more.

Her voice breaking, she spoke of the sense of loss in leaving her beloved New York apartment, of the sense of futility that all the information her brain had absorbed and processed over time, all the things big and small that she knew, would cease to exist with her death.

Nor could she find consolation in religion.

She had no faith in God or an afterlife. Those who had faith, she wished well: their hope was theirs, her despair was her own.

After the interview, RTE was deluged with messages from people, thanking her for her frankness and unique response to her illness. At the weekend, Marian Finucane said the great wave of response brought her consolation.

Why am I writing about this woman?

Well, she was a newspaper columnist and years ago, she said that in choosing a topic to write about each week, she sometimes had to resist the temptation to write about a big headline issue and listen instead to her head and heart and what was preoccupying them.

Since I heard on Saturday that she had died, she has filled my head and heart. I never met the woman, but when someone writes the way she did, you feel you know them intimately.

Her honesty put most of the rest of us in the media to shame. Whatever the issue, public or personal, Nuala O’Faolain faced it and wrote the truth as she saw it. Not the comfortable truth or the fashionable truth or the truth that fitted in with the thinking of those around her.

Even though she had a strong, mature intellect, her honesty had a child-like quality, delivered always without affectation or gloss. It showed first in Are You Somebody? peeling back the truth about her early years, and it showed a month ago, in the truth of that final radio interview.

Bookends, as she said herself, framing her life at the start and the finish.

My friend found himself thrilled and unsettled by the power of her presence all those years ago. Countless others since have been thrilled and unsettled by the power of her words. In her death, our world has lost a dangerous truth-teller.