When Jessy Park was eight, her mother, Clara, wrote a book about her. And to save her daughter any embarrassment in later life, she referred to her as “Elly”. More than 30 years after The Siege was published, Clara set to work on this sequel. Only now she could call Jessy by her real name, safe in the knowledge that she would never read the book, or understand why others might find the story of her first 40 years in any way interesting.

It’s not that Jessy can’t read. Aged eight, she was silent and uncommunicative. But now she talks and writes, paints and reads. She helps with the housework, manages her money - she even holds down a job in a university postroom. But embarrassment of the sort that her mother envisaged is not in her repertoire of emotions. For Jessy is autistic.

Precisely what that means is open to debate, variable from one person to another and subject to change without notice. Experts have suggested that autism is a sort of “mind blindness” - an inability to attribute beliefs, desires and emotions to others, or to grasp the significance of situations, especially of a social nature.

“At times,” her mother writes, “we have the eerie feeling that Jessy is a Martian, a visitor from some pure planet where feelings do not exist,” and it’s clear that her ability to get by in society is due in a large part to the unceasing work of Clara and others.

Jessy has had to learn by rote the sort of responses that come without bidding to the average baby. And always there is the sense that, without constant guidance and pressure, she would quickly fall back into the world of strange obsessions and bizarre mental loops that is the habitat of autistic people.

Jessy’s secret life, with its imagined “little imitation people” (this derives from her childhood mishearing of “Lilliputian”) and its compulsive calculations, is a source of limitless fascination. But it is her mother’s own quest for understanding, linked with her detailed reporting over four decades of progress, that makes it so valuable for those who live or work with autistic people.

For she asks the questions - Does Jessy’s autism make her unhappy? Does she know that she is different? What does she really think is going on? - that only she is in a position to ask. And as the father of a son who is touched by autism, I am grateful for such answers.

Some people may consider an account written by the autistic person of greater value, as it would give the “inside story”. But I have found such books difficult.

In the case of Lucy Blackman’s autobiography, this is not because of any shortcoming on the part of the author. Quite the reverse, for she tells of her early life in a large Australian household - her struggle to read and write with a keyboard while remaining virtually speechless, and her consequent coming to terms with her own autism.

In fact, it is her facility, not just with words, but also with people and situations, that is disorientating and distracting. This book is a testament to a remarkable young woman. But I needed more in the way of commentary and explanation than is provided in the brief foreword and afterword.

DAVID NEWNHAM