"We were refugees, we had absolutely nothing," recalls Sir Ralph, the youngest of five siblings.
"We were in a bit of a daze. We were in a new country that we did not know. We thought: 'What is going to happen to us next? Are we going to be sent back? Let loose? What are they going to do to us? Who is going to feed us? Where do we get clothes?' We did not know where we were going to get our next meal from. We had no house, no room, nothing."
He continues: "To me, it was a bit of an adventure. We managed to get out hours before Amsterdam was occupied. We left in the afternoon and in the evening Amsterdam was in the hands of the Nazis.
"Then we had a very adventurous journey. German planes machine-gunned us; thankfully they had already unloaded their bombs. Minutes before they shot at us, we were told to go below deck. The following morning, I saw machine gun bullets all over the top deck.
"But it was not an adventure for my parents. For them, it was a very hard, tough situation. We were penniless and destitute in a new country."
All that is a world away from Sir Ralph's present, smart office on Harley Street, with its walls lined with portraits of great men, including eminent pharmacologists he has worked with, along with impressive, framed certificates, an extract from the Talmud and two large tapestries, one of which depicts the Judgment of Solomon.
The wooden desk contains pictures of Sir Ralph's family: his wife Lady Zahava Kohn (a Bergen-Belsen survivor whom I meet on the stairs on my way to the office), their three daughters and grandchildren.
Sir Ralph, who received the Queen's Award for export achievement for his work in the pharmaceutical industry, is keen to stress that he owes his achievements to Britain.
In part, the former Salford Grammar School student, who won a scholarship to Manchester University after his family settled in Salford, is keen to support youth projects in a bid to back young people in the same way he was helped.
"What I have done for Britain is very little compared to the fact that they saved our lives, fed us when we had nothing and clothed us," says Sir Ralph, who was barmitzvah in Kersal Crag Synagogue on the day the Germans first bombed Salford. "They gave us opportunities to work, to develop ourselves. And the little I have done, Britain has recognised to the full."
Having lived in three countries before the age of 13, while growing up in a home where Yiddish, German and English were used interchangeably, does he now feel British?
"No," he says. "I feel very cosmopolitan.
"I can't say I am German. I was born there, but they didn't want me. I went to school in Amsterdam, but was never naturalised. We came to England, but I do not feel British. In order to really be part of the system, you must be born here.
"I have a British passport and I adore this country, it has been so good to me. They have honoured and helped me."
And, in return, he has helped Britain via the Kohn Foundation, which supports the arts, education, science and medicine. Sir Ralph politely brushes away questions on figures, but conveys his pride in the foundation's building of bilateral ties with Israel.
Last month, the Royal Society (of which Sir Ralph is an honorary fellow) signed an agreement with the Israel Academy of Sciences and Humanities to collaborate on research. The agreement was secured by a donation - reported to be in excess of £1.5 million - from the Kohn Foundation.
Hampstead-based Kohn, who has a home in Jerusalem, believes - "as a big supporter of Israel" - that collaboration between British and Israeli scientists is a paramount pursuit.
Having locked up his first violin in the Amsterdam flat, Sir Ralph took up singing and went on to train in Rome and New York before releasing 16 CDs. An international governor of the Israel Philharmonic Orchestra, he has performed at the Royal Albert Hall and Queen Elizabeth Hall.
So when is he at his happiest? "I am happiest when I can do things for which I have a passion," he says, reflecting on his career. "I set up the first independent clinical research organisation not beholden to industry or doctors. It is so important to find out what a drug does and report it clearly and honestly without manipulating data."
He adds: "I joined [the industry] at a time when great drug discoveries were being made. It was the beginning of the great drug revolution and I wanted to be a part of it through pharmacology."
And with the contributions Sir Ralph has made to science, music and philanthropy, it is still the values of his Orthodox family upbringing that he holds dear. Like his father, he still lays tefillin every day. "It is very important," he says.
"I am always learning - at university, I was combining university studies with yeshiva. Even today, twice a week I take private lessons on a one-to-one basis."
And, with that, the self-described cosmopolitan man, with an equally cosmopolitan accent, stands up to see me out of the office that he has occupied for the past 30 years.
