Author and journalist Thomas Harding was joined by his younger cousin, former Times editor and now BBC News chief James, for a revealing discussion about his new book at the JW3 centre last week.

Author and journalist Thomas Harding was joined by his younger cousin, former Times editor and now BBC News chief James, for a revealing discussion about his new book at the JW3 centre last week.

Hanns and Rudolf is the remarkable tale of “Nazi hunter” Hanns Alexander, the great-uncle of both Harding boys.

A German Jew who fled to England in 1936, Mr Alexander became a member of a British war crimes investigation team – and was the man who tracked down Rudolf Höss, the commandant of Auschwitz.

He later became a banker who lived to the age of 89 in Eton Road, Belsize Park, and never spoke of his experiences.

Thomas told the audience that it was only at his great-uncle’s funeral in 2006 that he learned of his part in bringing the mass-murderer to justice.

The writer, who grew up in Downshire Hill, Hampstead, was initially sceptical but set about uncovering the full story.

“I was motivated by my personal interest,” he said. “This was our great-uncle. I love the fact that someone in our family had gone back and done this, but more than that, he had broken rules, which is something I’m very fond of, something I can relate to.”

The evening at JW3, in Finchley Road, was something of a family affair, with the cousins’ relatives making up half the audience, including Thomas’s father Frank Harding, vice-chairman of the Heath and Hampstead Society.

James described the book as an “extraordinary, compelling and powerful story”, but admitted thinking that nobody would want to read it at first.

He went on to say it has now been published in 15 countries and enjoyed stellar sales since its release last month.

Let’s hope the BBC’s head of news is not losing his nose for a story.