I abandoned chemistry to concentrate on mathematics and physics. In 1942, I travelled to Cambridge to take the scholarship examination at Trinity College, received an award and entered the university in October 1943.

I was a close observer of the developments in molecular biology.

Leaving England was a painful decision, and we still have some regrets about it. However, at that time, the research environment for theoretical chemistry was clearly better in the U.S.

I had changed from being a mathematician to a practicing scientist. I was increasingly embarassed that I could no longer follow some of the more modern branches of pure mathematics.

In the war, most young men were inducted into the armed forces at the age of 17. A group of students was permitted to attend university before taking part in wartime research projects.

Life with a scientist who is often changing jobs and is frequently away at meetings and on lecture tours is not easy. Without a secure home base, I could not have made much progress.

I have had many opportunities to visit universities all over the world in the past 50 years.