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.

From an early age I was told that I was expected to do more than continue to run a small business. Education was important and seen as a way of moving forward.

I am delighted to have had students, friends and colleagues in so many nations and to have learned so much of what I know from them. This Nobel Award honours them all.

Our children were mostly brought up and educated in the Churchill suburb east of Pittsburgh. Each summer, we took them back to England for an extended period.

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

Looking through the list of earlier Nobel laureates, I note a large number with whom I became acquainted and with whom I interacted during those years as they passed through Cambridge.

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.