Biography: The name of Ernst Sedgwick Hanfstaengl suggests a pedigree of some complexity. His father was a Bavarian with a successful art reproduction business which included premises not only in the home town of Munich but also in London and New York.
His mother was an American whose father was German and whose own mother was from one of the leading New England clans, the Sedgwicks. Having picked up the nickname "Putzi" as an infant, which name stuck, the younger Hanfstaengl pursued as a child the study of the piano at the expense of the rest of the curriculum. However, he was being groomed to run the Fifth Avenue New York branch of the family business, so the next step in his education was Harvard.
After Harvard, through which he scraped, he lived and worked in New York - apart from one year of voluntary military service in 1910 in Germany - until his return, with wife and baby son, in the summer of 1921, to the defeated and downtrodden German state. By then, Adolf Hitler was beginning to flaunt himself.
Putzi was entranced from the first time he heard Hitler speak. He soon became the Nazi leader's intimate, playing the piano for him, entertaining him for Christmas Eve dinner on his release from prison in 1924, providing money for the Nazi party and choosing Hitler as the godfather of his son.
Putzi was useful to Hitler. Putzi had social cachet; Hitler did not. Putzi stuck around. In September 1930 he became head of Hitler's foreign press office.
Conradi describes Putzi's involvement with Hitler's entourage with a generous splash of social colour (Diana and Unity Mitford feature, with a good photograph of Unity and Putzi at the first Nuremburg rally in 1933). He also takes a look at some of the methods by which Putzi earned a few bob on the side (his lifestyle and finances were rarely in harmony) and at the world of intrigue and counter-intrigue as background to the bizarre circumstances in which Putzi fled Germany in February 1937.
Conradi then tracks Putzi's subsequent exile and internment in Switzerland, Britain and Canada.
However, the arrival in February 1942 of John Franklin Carter, "one of the more colorful characters in Roosevelt's entourage", gives the story a further fillip. Carter believed that as Putzi knew all the people in the Nazi government, "he might be able to tell what makes them tick". As a result, Putzi is extracted from internment and placed under a form of secret house arrest to write reports in comparative comfort, in the middle of nowhere, some 25 miles from Washington DC.
Whatever use he may have been to FDR in the intervening two years - and Conradi admits this is difficult to assess - it appears that by the summer of 1944 he could have become an electoral liability if his presence became known. So it was back to internment. Putzi's post-war years are spent justifying his past.
As his parting shot, Conradi delightfully suggests as an epitaph for Putzi his self- pitying quotation from 1943: "It is a terrible thing when you think you got on a bandwagon and it turns out to be a dustcart."
It hits the mark.
Hitler's Piano Player: A Biography, By Peter Conradi, Duckworth, 362pp. £20
John McBratney is chairman of the Tyrone Guthrie Centre at Annaghmakerrig and is a barrister