He is a self-professed yeshiva boy “born and bred” — hailing from a rabbinic dynasty that goes back 12 generations.

People flock to Rabbi Issamar Ginzberg, who lives in Jerusalem, for advice — but it’s not explanations of the Torah that they seek.

Thousands of companies, from start-ups to multi-national corporations including Google, seek-out Rabbi Ginzberg for bespoke business and internet marketing advice to boost their financial prospects.

Rabbi Ginzberg, born in Brooklyn, New York, has travelled the world speaking to company heads, employees and seminar groups.

He says the reactions of people to a bearded rabbi with peyot and wearing a long black coat is “interesting”.

I grew up without a TV in my house. It gave me a fresh look at companies

“I have been mistaken for someone who has come to the conference collecting charity; and I have been stopped from entering a hotel — even though I was the main speaker at the event,” he says.

“But I won’t change my appearance and pretend to be one of ‘the guys’. It’s better to be upfront to avoid any problems later. I am what I am.”

Rabbi Ginzberg, who has given lectures in Yiddish, Hebrew and English, has cultivated a reputation in the industry for recognising the overlap between business sales and consumer psychology.

But he prefers to travel abroad “to spend Shabbos with family in America. Most of my clients call me on Skype and put me on a screen in their conference room.”

The Chasidic rabbi, a father of four, believes that his expertise is strengthened by “wisdom of the Talmud and growing up with the Torah.

“Also, I grew up without a TV in my house. So not being exposed enabled me to have a fresh look at a company and product. My approach is infused with what I know. When people want free advice, I tell them there’s a [Jewish] saying: ‘If you don’t pay a doctor, his advice won’t work so well.’”

At around £600 for a four-hour package or £240 for a 60 to 75 minute consultation, Rabbi Ginzberg is not cheap. “People pay a hefty fee for a deeper level,” he reasons.

Rabbi Ginzberg has no university education but has always had an entrepreneurial flair. He says: “When I was eight-years-old, I would buy a box of cereal and sell it to others by the bowl.

“When I was a teenager, I was looking to make some money. I was paid $20 to pack shirts for a new company, and ended up redesigning a logo for the brand.

“By the time I was 19, I was being sent cheques by public companies.

“I read a lot and gained a tremendous amount of experience in the field. I learnt to never market a product — but to market a company.”

His ability to advise a breadth of clients, from charities and Israeli political parties wanting to increase donors; to a Hollywood studio trying to manage social media is helped by the fact that “80 per cent of business and psychology principles are the same,” he says.

“I like to dissect where those principles overlap and apply them.”