Derek, who received an OBE for services to the hospitality and tourism industries, told me: "I didn't start writing Jewish history books till 2005.

"You have to re-invent yourself when you are very old because you can't go on forever building hotels, which I did for 25 years. I have written 12 books about hotels and hotel history and eight books about Jewish history."

In the last year, Derek has produced three books and is currently writing two more.

Like his first Jewish history book, British Chief Rabbis 1664-2007, his most recent publication, Chief Rabbi Hertz - The Wars of the Lord (Vallentine Mitchell), deals with the United Synagogue and the British rabbinate with which Derek's family has many historical ties.

Derek's maternal great-grandfather, Joseph Freedman, who began his British working life as a pedlar in the Welsh valleys and then went on to make a fortune out of hire purchase furniture shops, is mentioned in the book for having subsidised Joseph Hertz's Soncino Chumash and chaired the United Synagogue Building Committee in the 1930s.

"My family have been United Synagogue supporters since 1870," Derek said. "Members of the family have served as wardens all over London.

"I was brought up in Golders Green Synagogue. I spent many years at the Central Synagogue and we are now members of Hampstead Garden Synagogue. Nothing has changed."

Derek's father began as a choirboy at the Central Synagogue, after which he served for 15 years as synagogue warden.

His uncle headed the Board of Shechita and was a warden at Golders Green Synagogue.

Derek, who was married at Manchester's Higher Crumpsall Hebrew Congregation to Diane Millman, of Southport, was educated at the Jewish boarding house Hillel at Perse School, Cambridge, and then at Jesus College, Cambridge, where he read history.

"I went to boarding school because there was a war on and there were bombs dropping all over the place," he said.

"I only went back to London during holidays. When the war broke out I was seven. We were evacuated to Bournemouth for a few days, then to Worthing and Hampshire.

"One moved around wherever the bombs weren't dropping.

"Perse was the village school for Cambridge. No-one ever thought of going anywhere else but Cambridge University. We didn't apply for any other university.

"The relationship between the university and the school was pretty strong."

Last year Derek published a book on the history of Hillel House, Perse School.

He explained his attitude to Jewish history: "If you have a history degree, you are taught straight down the main road of dates and events and things like that.

"It's only when you graduate that you have the rest of your life when you wander around the back streets and look at all the things you didn't have time for when you were studying for a degree.

"When you start to look at Jewish history, there are a lot of Jewish history books about the Jewish community, which are not really written according to academic standards.

"The most important thing about academic standards is that no-one should ever know what your own personal views are.

"If we do our job properly we write the facts, but we don't try and distort them to whatever views we may have.

"I hope that if people read my books, they won't know what my views are, but they will know the truth about what actually happened."

Derek gave the example of the British Masorti movement trying to call Hertz one of theirs because he attended the American Jewish Theological Seminary while it was still strictly Orthodox before it was taken over by the American Conservative movement.

He said: "To try to take Hertz and make him into a Conservative rabbi is to distort the truth. He was never anything other than a totally Orthodox rabbi.

"The job of Hertz was to ensure that the vast number of immigrants who came into this country from 1880 onwards remained within the Orthodox fold, rather than the situation in America where the large majority became Reform.

"It's very odd that the community in this country remains primarily Orthodox. This isn't typical.

"It's down to Hertz and Chief Rabbi Nathan Marcus Adler before him. I'm writing a biography of Adler at the moment. He has been underestimated for a very long time."

Derek is also simultaneously writing a history of Jews' College.

His current book on Hertz shows how the Austrian-Hungarian born rabbi, who was educated in America, was a fighter who was always prepared to stand by his convictions and defy his lay management, whether it be in the political arena when he served in South Africa or in pre-war Britain or in the religious sphere when he had to stand up to the liberalising tendencies of his United Synagogue president Robert Waley Cohen.

Derek's first Jewish book was on the history of British Chief Rabbis, starting from the Sephardi Haham Jacob Sasportas Haham in 1664, covering all the 21 Ashekenazi and Sephardi Chief Eabbis.

He explained why he was so fascinated by the British rabbinate: "It is a field which has been sparingly covered.

"The rabbinate is fundamentally responsible for the continuation of Orthodoxy in this country. The rabbinate has kept the community where it is today. Nobody has ever really given them a great deal of attention."

But Derek's next book was about the 1847 Don Pacifico incident when British foreign secretary Lord Palmerston sent a fleet of six battleships, three cruisers, six destroyers, 750 guns and 6,000 marines to blockade Greece till the Gibraltar-born Jew David Pacifico received compensation for government-sponsored antisemitic attacks.

He then wrote a biography of Solomon Schonfeld, who brought over many Nazi refugees, working closely with Chief Rabbi Hertz, who became his father-in-law.

Together with Greville Janner, Derek then wrote a history of Jewish parliamentarians, covering several hundred British MPs.

Next came A History of The Sunderland Beth Hamedrash, commissioned by the congregation.

In 1860, Derek said, Sunderland's Rabbi Solomon Schiller-Szenessi revolted against the London-centric nature of the United Synagogue under Chief Rabbi Nathan Marcus Adler.

Derek's next book was Thank You For Your Business - The Jewish Contribution to the British Economy, with a foreword by Chancellor of the Exchequer George Osborne.

Chief Rabbi Hertz: The Wars of the Lord is available to Jewish Telegraph readers at a 20 per cent discount, call 0208 952 9526.