I think anyone who is beginning to realise that old age is actually going to happen to them (people like me perhaps, who find that the age of 50 is not in the distant future any more, but just round the corner) should read this book. It is a hopeful book, for all that it mentions the limitations of old age. Not that we could all write a book in our 80's, let alone several, but the knowledge that it is possible to discover new delights in old age is reassuring.
The reason why I have given this book 4 rather than 5 stars is Diana's total lack of remorse for sleeping with other women's husbands. She may well not believe in the "possessiveness" of marriage, and states that she never wanted to take the husbands away from the wives, but those defences are missing the point. When a woman discovers that her husband has kept a mistress, she feels betrayed. She has been betrayed. To be part of betraying other women is not excusable simply because you go to a lot of effort to keep that betrayal hidden. That is akin to believing that it is morally acceptable to steal from people who have dementia. And I do not use that example because I think it is possible to steal a person - people are not things, but a husband by definition has made promises to someone about their fidelity - promises that a mistress enables them to break. There is a moral aspect to knowingly enabling someone to do something that hurts another.
And so, as I found reading about that unpleasant, I have had to dock a star from my review.