Nica, who was born in 1913, grew up at Tring Park (Tring is now a school; Waddesdon Manor, though administered by a trust under the chairmanship of Hannah's father, Jacob, was bequeathed to the National Trust in 1957). There, she wiled away her young days in a starched white dress, sewing and playing the piano; her parents did not approve of education for girls and running and hiding were forbidden lest her frock be ruined. Life was monotonous and dull but, knowing nothing else, she did not think to kick against it.
In 1934, she was duly presented at court and her marriage in 1935, to Baron Jules de Koenigswarter, a handsome French diplomat, was predictable, if not the soaring match her ambitious mother had dreamed of. If he was controlling, well, she was used to that.
In 1948, however, something happened. On her way to the airport after a visit to New York, Nica stopped to visit a friend, the jazz pianist Teddy Wilson, who played her a recording of "Round Midnight" by a then unknown jazz pianist, Thelonious Monk. Unable to believe her ears, she listened to it 20 times in a row and was bewitched. Having missed her plane, she never went home again.
Abandoning her husband and five children, she moved into a suite at the Stanhope hotel and set about trying to meet the man who had made this extraordinary record. Naturally, it took a while to track the erratic Monk down. It wasn't until 1954 that she finally laid eyes on him, having flown to Paris for the privilege. Did he live up to her dreams? Oh, yes. He was, she said, "the most beautiful man she had ever seen". From that moment, there was no going back. For the next 28 years, Nica devoted her life to Thelonious Monk. In her eyes, he could do no wrong. He was a genius, pure and simple, and there was nothing she would not do – no money she would not spend, no place she would not go – to make his life easier.