I stand in the archway of the building where Dr Eduard Bloch had his home and surgery: the Palais Weissenwolff at No. 12 Landstrasse. Embedded in the wall is a beautiful, wrought-iron disc bearing the words Haus Glocke (House Bell) running in raised letters around the outside.

The bell button itself, in the middle, is chipped and yellow like a nicotine-stained fingernail; a crack arches its way over the surface, evidence, perhaps, of the desperation with which the bell was rung repeatedly by the many people seeking Dr Bloch’s services.

I know that the well-liked doctor took his calling very seriously. In all weathers, at all hours, he would put on his big black felt hat and drive his small horse-drawn carriage out to visit his patients at home.

‘I never made the slightest distinction between the treatment of rich and poor,’ he asserted in his later handwritten memoir. ‘I answered the call of every sick person, even in the coldest of nights, so that my constant readiness to help became almost proverbial.’ No wonder that in its heyday, Eduard’s medical practice was one of the most successful in Linz.

I turn my attention to the two large marble figures of Atlantes at the Palais Weissenwolff. The stonework is grubby, and the figures look careworn, slightly slumped, as they struggle to bear the weight of the first-floor balcony on the back of their heads and necks. Looking up at the balcony itself, I try to imagine what it would have been like for Eduard to witness Hitler’s triumphant return to the town where he grew up. The photographs and Eduard Bloch’s own account bring the scene vividly to life.

It is March 12, 1938. The crowds pack, seven or eight deep, along the pavement in front of the Palais, waiting excitedly for the arrival of the Führer.

The early morning spring sunshine has helped tempt people out of their apartments and houses without heavy overcoats. Everywhere, there are now red, black and white flags emblazoned with the Hakenkreuz (Swastika).

Church bells are ringing, planes drone overhead, and loudspeakers relay the slow progress of Hitler’s convoy, travelling east from Braunau on the Austrian border, a border that no longer has any relevance. As Hitler’s large, open-top Mercedes finally noses its way along the Landstrasse, the crowds erupt, and there is an orgy of flag-waving and straight-armed salutes. For one thing, they are expressing their delight that Hitler has chosen Linz, his favourite Austrian city, as the first stop on his victory lap of Austria.

Eduard Bloch stands inside by his first-floor window to watch Hitler’s motorcade roll by below him. It is a moment he will never forget:

I stood for a short time at my window full of anxious anticipation at the arrival. Standing up in his slow-moving car, Hitler saluted in all directions, including up at my window; I assumed that the salute was not meant for me but for one of my neighbours who was an enthusiastic Hitler-supporter. I was informed the next day that this ‘honour’ was meant for me. Straight after his arrival at City Hall, the Führer asked after me.

Eduard’s daughter Trude later remembers that the following day a town councillor, Adolf Eigl, recounted Hitler’s very words to her: ‘tell me, is my good old house doctor, Dr Bloch still alive? Yes, if all Jews were like him, then there would be no antisemitism.’ Trude can, she says, ‘swear to it.’

In truth, this is not a new revelation. Eduard has already heard messages about Hitler’s continued fondness for him, from his patients who made the short journey from Linz to visit Hitler at his Alpine retreat of Berchtesgaden.

He knows, therefore, that Hitler thinks him an exception, an Edeljude, a noble Jew. He has already been told verbatim what Hitler said about him: ‘If all Jews were like him, there would be no Jewish Question.’

The doctor admits later to thinking that ‘Hitler could at least see something good in one member of my race.’ Standing at his window, it is clear that Eduard has very mixed feelings and cannot help being a little proud at seeing the ‘frail boy’ he treated so often, and whom he has not encountered for 30 years.