After I- I left the National Institute and moved to University College, I did two things. One of them, I was running quite a large group of immunologists and in the course of trying to make ourselves useful to- to cancer, we got fairly far into viral immunology. I think that was not entirely a good thing because I think viruses have turned out to be less important in cancer than was thought at the time, not necessarily by everybody, but some people thought it was more important, and various other things. But at the same time, I jumped ship up to a point, and started working for WHO and I had no regrets about that. Why- why should I? I very much enjoyed working for- first for the tropical disease research in WHO, and then in their contraceptive vaccine programme. But if you get sucked into WHO, what do they call them? WHO, World Holidays Organisation. It certainly takes you around the world. Where before I knew only 10 immunologists, then I started to know hundreds and then a thousand, and many of them have dark faces, and those dark faces are among the best scientists I've ever known. So the vaccine approaches to contraception haven't really taken off. Do you think they will? Possibly. I certainly think that they haven't been excluded. I think the- there- it was a programme which made sense. It was one devised by various people. From my point of view, Pran Talwar in Delhi was the man who was pushing it hardest, so he ran a contraceptive trial which was more or less successful in the sense that a large number of women were protected against conception for a period of some months. It ran into the problem that only 80% of the women did make antibodies, enough antibodies to protect themselves against pregnancy by recognising their own human gonadotropin. That set the work back, but they were- that's a trivial problem really in the- in the history of immunology. We've learnt how to make better antibodies and there are recipes being tested for making antibodies now.