On my return to Pittsburgh, I resolved to go back to the fundamental problems of electronic structure that I had contemplated abstractly many years earlier.

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

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.

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 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.

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.