I suppose the really first influence I had was RW James in Cape Town. He was a... he became an FRS later, rather late, but he was a... first class scientist and he brought the... what you might loosely call 'the English empirical system' and also 'the Cambridge system' into Cape Town, to Cape Town University, and he also... taught me a... not taught me, but we had experiments on optics of an unusual classical kind, and so I learnt about coherence, Birefringence, and things like that, all of which teach you something. And of course, he also introduced me to X-ray crystallography, and that's what a large part of my later work was based upon, X-ray crystallography. I also learned there... I suppose I learned from him that I could do a project and even do things like build apparatus and so on, learn how to measure intensities, all small things but things like that.

And then going into Cambridge, I had very little influence from my Supervisor [Douglas] Hartree didn't really... the subject, and I went to a lot of lectures and sat in on different things, and I learnt quite a lot of mathematics, I learnt more mathematics. But I think the person who influenced me the most was originally Rosalind Franklin, and what she taught me I guess was the importance of tackling important problems, even difficult and long term problems. I say she taught me, it was by example and so I was very lucky to find her. Luck is terribly important in all this. People say you should choose your mentors, but you can't choose your mentors, because you can't just say, 'I want to come and be your disciple.' It doesn't work like that. I was lucky to find an RW James, Reginald William James... in Cape Town, lucky to find Rosalind Franklin at Birkbeck, though I didn't go there... lucky to have a disagreement with Harry Carlisle... you know that was sort of educational... when I learnt.

And then later on, Francis Crick, of course, and he's probably the... I don't know if he's the biggest influence because I'm not like him, but he... I did watch, I think I said earlier, watch how he went about problems and the kind of excitement that he... he had great powers of concentration. He could concentrate for six to eight hours on a subject. I also learnt from him... Newton could do 22 hours, by the way, so he wasn't Newton. But the... that you had to keep things in your mind for a long time, I think I learnt it from him. And one way of keeping things in your mind is to read papers on the subject, even if they're not good papers. Francis used to say to me, he read all these papers on chromatin. I said, 'Look, they're horrible papers.' He said, 'You never know where you might find some kind of slight observation or some anomaly or something of that sort which might help us.' I don't think he ever found one, but what it did was to concentrate your mind on the subject over many weeks, months, and even years.

And I can't think of any... I have, I have sometimes been asked who my scientific heroes are. But that's different, who your scientific heroes are. But if you ask that question as well, Crick would be one of them. And I don't think there's been any others, any other big influences. Bernal I thought could have been an influence, but he never... Bernal, I learnt also... I did learn from Bernal, and from Bernal I learnt what he didn't do, which was to attend to the details. That's also learning. Bernal, although he had suggested many things, he never stuck and looked at the details of any of the processes. He wasn't like that, whereas Francis who had a mind at least, if not greater, than Bernal's actually read all the small print, all the boring stuff, and so on, and not always with much profit.