I was born in 1926 to Lazar and Bella (née Silin) Klug in Zelvas, Lithuania, but remember nothing of the place, because I was brought to South Africa as a child of two and grew up there. My father was trained as a saddler, but in fact as a young man worked in his father’s business of rearing and selling cattle, so he grew up in the countryside. He had a traditional Jewish education and secular schooling, and though not a conventionally well educated man, he had some gift for writing, and had a number of articles published in the newspapers of the capital, for which he acted as what would now be called a stringer. Shortly after I was born he emigrated to Durban, where members of my mother’s family had settled at the turn of the century, and the rest of the family followed soon thereafter.

Durban was then a relatively sleepy town in subtropical surroundings. It was a fine place for a boy – there was the beach and the bush and school was not too taxing. I went to a good school, Durban High School, which was run on traditional English lines, with a curriculum somewhat adapted to South African circumstances. We had some good masters particularly in History and English. However, by the standards of to-day, there were few challenges other than Advanced Latin Prose Composition in the 6th Form. The philosophy of the school was quite simple – the bright boys specialised in Latin, the not so bright in science and the rest managed with geography or the like. There was a good library but it was the playing fields that kept one out of mischief. I did not feel a particularly strong call to any one subject, but read voraciously and widely and began to find science interesting. It was the book called Microbe Hunters by Paul de Kruif, well known in its time, which influenced me to begin medicine at university as a way into microbiology.

At the University of Witwatersrand in Johannesburg, I took the pre-medical course and, in my second year, I took, among other subjects, biochemistry, or physiological chemistry as it was then called, which stood me in good stead in later years when I came to face biological material. However, I felt the lack of a deeper foundation, and moved to chemistry and this in turn led me to physics and mathematics. So finally I took a science degree.

I had by then decided that I wanted to do research in physics and I went to the University of Cape Town which was then offering scholarships which enabled one to do an M.Sc. degree, in return for demonstrating in laboratory classes. The University lay in a beautiful site on the slopes of Table Mountain, which one climbed at week-ends. I was lucky to find as Professor there, R.W. James, the X-ray crystallographer, who had brought to Cape Town the traditions of the Bragg school at Manchester. He was an excellent teacher and I used to attend his undergraduate lectures as well as those in the M.Sc. course. From him I acquired a feeling for optics, and a knowledge of Fourier theory, and I remember particularly certain optical experiments on rather abstruse phenomena such as external and internal conical refraction which fascinated me. After taking my M.Sc. degree, I stayed on and worked on the X-ray analysis of some small organic compounds, in the course of which I developed a method of using molecular structure factors for solving crystal structures, and taught myself some quantum chemistry to calculate bond lengths and so on. During this time, I developed a strong interest, broadly speaking, in the structure of matter, and how it was organised. I had now acquired a good knowledge of X-ray diffraction, not only through my own work, but through having helped James check the proofs of his fine book – The Optical Principles of the Diffraction of X-rays – still a standard work. James wrote beautifully and fully and took great pains to make everything clear.

Supported by an 1851 Exhibition Scholarship and also by a research studentship to Trinity College, I went to Cambridge in 1949. Cambridge was the place for someone from the Colonies or the Dominions to go on to, and it was to the Cavendish Laboratory that one went to do physics. I wanted to work on some form of “unorthodox” X-ray crystallography, for example protein structure, but the MRC Unit where Perutz and Kendrew were working was full, and Bragg, then the Cavendish Professor, had closed down a project on order – disorder phenomena in alloys, which interested me. I finally found myself a research student of D.R. Hartree, who had been a colleague of both Bragg and James at Manchester. He suggested to me a theoretical problem left over from his work during the war on the cooling of steel through the austenite-pearlite transition, and I learned a fair amount of metallurgy in order to understand the physical basis of the phenomenon. It turned out however in the end that it was not special crystallographic insight that was called for – the course of the transition was in practice governed by the diffusion of the latent heat and I ended up using numerical methods to solve the partial differential equations for heat flow in the presence of a phase transition. I learned a good deal during this time, particularly in computing and solid state physics, and the idea of nucleation and growth in a phase change had its echo when I came later to think about the assembly of tobacco mosaic virus.

After taking my Ph.D., I spent a year in the Colloid Science department in Cambridge, working with F.J.W. Roughton, who had asked Hartree for someone to help him tackle the problem of simultaneous diffusion and chemical reaction, such as occurs when oxygen enters a red blood cell. The methods I had developed for the problem in steel were applicable here, and I was glad to put them to use on an interesting new problem. The quantitative data came from experiments in which thin layers of blood were exposed to oxygen or carbon monoxide. In the course of my stay there, I also showed how one could analyse the experimental kinetic curves for the reaction of haemoglobin with carbon dioxide or oxygen by simulations in the computer, and so fit the rate constants.

This work made me more and more interested in biological matter, and I decided that I really wanted to work on the X-ray analysis of biological molecules. I obtained a Nuffield Fellowship to work in J.D. Bernal’s department in Birkbeck College in London and I moved there at the end of 1953. I joined a project on the protein ribonuclease, but shortly afterwards met Rosalind Franklin, who had moved to Birkbeck earlier and had begun working on tobacco mosaic virus. Her beautiful X-ray photographs fascinated me and I was also able to interpret some pictures which had apparently anomalous curved layer lines in terms of the splitting which occurs when the helical parameters are non-rational. From then on my fate was sealed. I took up the study of tobacco mosaic virus, and in four short years, together with Kenneth Holmes and John Finch, who had joined us as research students, we were able to map out the general outline of the structure of tobacco mosaic virus. This work was done partly in parallel with that of Donald Caspar, then at Yale, but he spent 1955 – 56 in Cambridge, and I formed an association with him which continued across the Atlantic for many years. It was during this time that I met Francis Crick and we published a paper together on diffraction by helical structures. I was fortunate to work with him again later, and so be able to learn, as he once wrote of Bragg, from watching the way he went about a problem.

Rosalind Franklin died in 1958 and, supported by an N.I.H. grant, Finch, Holmes and I continued the work on viruses, now extended to spherical viruses. We were joined soon after by Reuben Leberman, a biochemist. In 1962 we moved to the newly built MRC Laboratory of Molecular Biology in Cambridge which, under the leadership of Perutz, was to house the original unit from the Cavendish Laboratory (Perutz, Kendrew, Crick and, later, Brenner), enlarged by Sanger’s group from the Biochemistry Department and Hugh Huxley from University College London. I was thus privileged to join the laboratory at this stage in its expansion and so be able to take advantage of, and to help build up, its unique environment of intellectual and technological sophistication. The rest of my scientific career is largely a matter of record and much of this is dealt with in the lecture that follows.

However, I should perhaps add that during the 20 years I have been back in Cambridge, I have been actively involved in the teaching of undergraduates, as well as of course supervising research students. I am still a Director of Studies in Natural Science at my College, Peterhouse, and under the tutorial or – as it is called in Cambridge – supervision, system, I teach undergraduates myself. I like teaching and the contact with young minds keeps one on one’s toes, but increasing responsibilities have forced me to shed much of it in recent years.

Before I came to Cambridge I married Liebe Bobrow whom I had met in Cape Town. She trained in modern dance at the Jooss-Leeder School in London and later became a choreographer and coordinator for the Cambridge Contemporary Dance Group. More recently she has directed and acted in the theatre. We have two sons, Adam and David, born in 1954 and 1963. Adam, after studying History and Economics at Oxford and the London School of Economics, is now doing research in Econometrics. David is a second year student of Physics.

This autobiography/biography was written at the time of the award and later published in the book series Les Prix Nobel/ Nobel Lectures/The Nobel Prizes. The information is sometimes updated with an addendum submitted by the Laureate.