I can’t pretend I relate that closely to any of the crop of candidates for the Conservative leadership, but over these last few weeks I think I might have got a small inkling of what they’re going through. For I too have been in campaign mode, “taking my message up and down the country” as the Tory hopefuls might put it.

That’s only a small exaggeration. I’ve been making my pitch to audiences in almost every corner of the British Isles, from a tent in Wales to a marquee in the Scottish countryside, from the Victorian majesty of Bradford town hall to an arts centre in the small Channel island of Guernsey.

True, I’ve not been insisting that I can “take Britain forward” or that “I have the vision and experience to win”, but just like Rishi, Liz and the others I have been making a case. Because I’ve been talking about my new book, The Escape Artist. It tells the story of Rudolf Vrba who, along with Fred Wetzler, broke out of Auschwitz in April 1944 to warn the world of the truth of (what was not yet known as) the Holocaust — and argues that that story deserves to be ranked alongside those of Anne Frank, Oskar Schindler and Primo Levi as one of the defining narratives of the Shoah.

Inevitably some of the questions that have come my way recur. How did I come across the story and why did I want to tell it now? Why aren’t Vrba and Wetzler more famous? How did I manage to wade into the depths of detail about the barbarism of Auschwitz without sinking into bleakness and despair?

And yet nothing about these encounters is repetitive; no two are ever the same. That’s not because the story itself changes but rather because every audience comes at this subject from a different perspective, a different history and a different experience.

It means the points of discomfort are different. At, say, a Bradford or Hay festival, the part of my message that is perhaps hardest for people to swallow is the talk of Allied, and specifically British, reactions to the Vrba-Wetzler report: the two escapees’ detailed, 32-page account of what they had seen in Auschwitz. Our fellow Britons naturally want to hear that Winston Churchill, who is all but the patron saint of modern Britain, did the right thing the instant he learned of the horrors of the death factory. So they’re glad to learn that Churchill’s response to Vrba and Wetzler’s testimony and the plea Jewish leaders had attached to it — urging the Allies to bomb the railway tracks to Auschwitz — was to instruct his foreign secretary, Anthony Eden, to get everything out of the Air Force he could, “and invoke me if necessary”. But then they have to reckon with the fact that the Air Force said no — and no action was taken.

At JW3, the tension arose from the inaction of a different player in the drama, as I explained how the de facto leader of Hungarian Jewry, Rezso Kasztner, failed to distribute the report — and warning — that Vrba and Wetzler had worked so hard to produce. The Kastzner episode polarises opinion in Israel even today, but it has a neuralgic history for British Jews too: because Kasztner was a Zionist, his conduct has been used by Zionism’s most unbending critics to discredit the entire movement. That has led to some reluctance to face the facts of what Kasztner did — and did not do. So to mention his name to a Jewish audience is to see backs stiffen.

Guernsey was something else again. I realised that at all the previous events I’d done, the audience could tacitly assume that, had they lived through the period I was describing, they would — obviously — have been on the side of right. And yet, as I spoke of those who had colluded with the Nazi plan to eradicate the Jews, whether in Slovakia or Nazi-occupied Poland, I soon sensed that for a Channel Islands audience, none of this was so straightforward. The generation of their parents or grandparents had lived under Nazi occupation and many approached me afterwards to say, sometimes in whispers, how not every islander had behaved nobly, how some had failed the moral test history had presented them. For many, Vrba’s story struck an uncomfortable nerve.

But if the differences between these various audiences have been striking, so too have the similarities. The truth is, the intensity of response to this book has caught me by surprise: everywhere I’ve talked about it, people have been hungry to hear this story, to learn every detail of it they could.

The world-weary explanation for that is, to borrow the title of Dara Horn’s excellent collection of essays, People Love Dead Jews, with the enduring interest in the Shoah the firmest proof. But I prefer a less cynical reading. People are indeed fascinated by the Holocaust, but that’s because they still see it as a guide to human nature. It tested people in the most extreme way imaginable and in the process revealed who they — and therefore we — are.

There’s one last event I ought to mention, which also happened to be almost the first. It was hosted by the Holocaust Education Trust and there, in the front row, sat several survivors. To speak about the Shoah to survivors of the Shoah is a daunting prospect indeed.

And yet it was their reaction that gave me great heart for all that was to follow. For they were pleased I had written this book. No matter how much time has passed, they are insistent that the story of the Holocaust be told — and remembered.

‘The Escape Artist’ by Jonathan Freedland is published by John Murray Press (£20)