Thank you for the suggestion! I will definitely read Mary Soames’ books!
A curious book on the same subject I bought for a couple of dollars is Violet Bonahm-Carter’s memories of Churchill. Probably not a masterpiece but I am sure that it will provide some interest insight on the man.
Read some of the interviews she gave; she was a fascinating interviewee, (she died in 2014, lucid to the end), funny, objective, articulate and firm - she loved her parents but wasn't blind to their flaws, and very aware that she had the privilege of a ring side seat to history.
For a variety of reasons, (one of which was the close bond she had with her governess, who remained the same all though her childhood and teens, giving her a stability and security her siblings lacked), she had a different childhood to that of her siblings. Another may have been that she was never considered to be quite as 'glamorous' as some of her siblings, physically, as she said herself, she was stocky and dumpy, resembling her father, whose literary skills she also inherited.
When the war came, and her father became PM, she insisted on enlisting (unheard of from her background) in the armed forces - Churchill had made a speech about the need for women to become involved in the war effort, and she apparently threw it at him.
She always said that enlisting - she was later commissioned and later still, Churchill used her as an ADC at the some of the famous conferences that closed the war, where, as a young woman in her early twenties, she saw history unfold in front of her eyes - was the very best thing that ever happened to her, as she learned, first-hand, what the lives of people who were not from the upper-class were like, and it knocked some off some of her edges.