Julia Neuberger recalls novelist Naomi Mitchison who is 100 this year.

Anyone who has ever met Naomi Mitchison - Nou, as she is commonly referred to - will have taken away an impression of an incredible energy and passion for life.

Even in extreme old age, she is not a restful person. She has more to do, more to say, more to think, and the infirmities of age are irritants and worse. All this is conveyed strongly in Jenni Calder’s portrait, with its strong sense of Nou’s restlessness, of her sociability - almost to the point of fear of being alone. We also read of Nou’s complicated relationships with her children, and with others, as we learn how she made Scotland her home, Botswana her home, Oxford once again her home, acquiring new identities and pushing out the boundaries of belonging all the time.

But none of this conveys the essential Nou. In my twenties, I stayed at Carradale in Scotland with my husband, by invitation of one of Nou’s grandsons, Neil, who had been best man at our wedding. I had just had major surgery, and was feeling a bit pathetic. (Some of us felt quite pathetic in that household even if we had not had surgery shortly before - the energy in the place was palpable!) Nou was kindness itself. Unlike the other “young”, who were sleeping in cottages and so on, we were given a rather grand bedroom, and she asked often about how I was feeling - not out of hostessly duty, but out of real concern.

Equally, the humour is missing from Jenni Calder’s rich account. Nou is not, on the whole, one to laugh at herself. But she can, and could, see the funny side of things. That charm does not fly off these pages, though Nou in person in Dublin at her grandson’s wedding in a Catholic church (when many of her avowedly atheist family refused to enter that papist building) was deliciously pointed in her teasing of her “Protestant” relatives. Or Nou at lunch in the old days at Val and Mark Arnold-Forster’s house would see some young man eating enough for a week, and josh him about economising the rest of the time.

Large family meals, friends around a table, have always been important to Naomi Mitchison. Jenni Calder conveys the social person, conveys the sense that life was to be lived in a crowd, that friends, lovers, colleagues, all had to share food, though she points out the sparseness of food on some occasions at Carradale, without pointing out at the same time that this went in many ways against the grain. Nou was a generous hostess, if sometimes a vague one. What she wanted - and succeeded in achieving - was a multi-generational household, with witty and intellectual conversation, and a sense of buzz.

That sociability, sometimes excessive, has been a life-long characteristic. Much more unconventional have been her passions - her passions for other men, in her open marriage to Dick, which Calder suggests began to show fissures partly as a result of that desire for experimentation. Nou had a passionate affair with Theodore Wade Gery, the relationship that hurt, and the one where she could not get her way. Dick, her lovely supportive husband, had relationships as well - Tish Rokeling, his last and longest extra-marital love, came to see him at his end. Nou had been less and less in tune with him after he became an MP and then a peer, while she was becoming a Scottish laird. Their ways parted, though the loyalty remained.

That picture of their marriage is the most compelling feature of Calder’s book. Despite Nou’s many other passions - Scotland, Botswana, birth control, radical politics, feminism - it is the personal which emerges most strongly. Her writing has coloured her life, yet this book is often surprisingly short on quotations from Nou’s works, particularly in her middle period, and disappointingly dismissive - as Nou herself is - of some of the novels that were very popular in their time. Jenni Calder is also badly let down by lack of copy-editing - mistakes such as “Frascism” for “Fascism” and “repurcussions” for “repercussions”, to cite but two of many, should not have got through into print.

This is a volume that should be read for a portrait of a century as much as of a person. Through Nou’s eyes, we see times change, and her trying to change them. A pusher-out of boundaries, Naomi Mitchison contributed much to debates about women’s lives and women’s sexuality. I would have liked more warmth in this volume, and more of a sense of the private writer than Jenni Calder has achieved, but as a portrait of a remarkable woman who defied convention and lived her life to the full, it is a fine piece of work.