By '46,'47 or so, I had decided that I did not want to spend the rest of my life being an engineer. It was partly that I suffer quite severely from myopia and astigmatism... there was no way I was ever going to be able to fly an aeroplane. And to spend your life designing things you can't fly is a bit impotent, you know, and I never really liked aeroplanes, in consequence. And I knew... although I'd enjoyed being an engineer, I don't want to get... get you... get me wrong here, I genuinely enjoyed the skills of designing things. I didn't want to do it for the rest of my life. And I hesitated between physics and biology. I knew I wanted to get into academic science, in other words. I thought physics - I think, rightly - I thought physics was too difficult. I'd never make an experimental physicist, any piece of apparatus I touch, breaks, on... there are people like that, and I'm one of them. I simply am not technically good enough to be a theoretical physicist, it's just terribly, terribly hard. I mean, you know, I knew some theoretical physics, I knew what Schrödinger had done, I knew what Einstein had done, so the idea that I could ever do anything like that - no way, just too hard. Whereas biology looked rather easy, and as a matter of fact, as you know, it is, I mean, any idiot can be a biologist, roughly. So I had to... I had to decide to go for biology. And I decided to go back to college. I'm not sure that was necessary. Maybe I could have got straight into post-graduate biology, I don't know, but I think it wasn't a bad idea really. And I... I just enrolled as an undergraduate.

[Q] How old were you when you re-enrolled?

27. It wasn't difficult then, remember, so many of contemporaries who'd spent the war, not designing aeroplanes but being shot at in the Army or the Navy, were also coming... leaving the services and going back to college. So, when I was an undergraduate at University College, you could tell the students from the staff because we were older and more sensible and so on, you know. It was rather a nice time to be a student, actually. So it wasn't that I was... we were a mixture of kids straight out from school, and people who were in their late 20s who'd been through the war. And we made a nice community, actually, a very nice community. And I went to University College essentially because I knew Haldane was there, and I'd been, as I think I said earlier, greatly influenced by his writings. He also shared with me being an old Etonian, he shared with me being an ex-Marxist, or actually, at that time, sort of still formally a Marxist, though like me he was going through the same kind of turmoil over Lysenko and so on, that I went through. And I thought: Well, you know, I would like to learn under this guy. And I mean, whether I... I didn't know just how difficult a person he was but intellectually, I couldn't have done better. I mean, he was marvellous.