‘I don’t know of anyone in comparable middle-class peacetime circumstances who did what my father did.’ Michael Christiansen’s unique crime was walking out on his wife, baby daughter and four-year-old son, Rupert. It was 1959, a period when divorce was still ‘a dirty word, literally unspoken in polite society’. Rupert’s mother, living in the middle-class London suburb of Petts Wood, was ‘subtly degraded – looked at, talked about, pitied from a distance and by tacit agreement marked down as a danger area’. As a divorcee, she was told by the vicar that she could not receive communion or join the Mothers’ Union. No wonder she was bitter. Michael persevered in sending Christmas and birthday presents, he tried to take his children out on Sundays, but his attempts at keeping in contact soon fizzled out in the face of his ex-wife’s hostility.

After that, as far as Rupert knew, she and her children had absolutely no contact with their father, either in person or by letter or telephone, until the day he died, a quarter of a century later. The children were resilient. They adored their mother and wiped out any memory