After the war in 1947, he developed an interest in endocrinology and reproduction and started a small animal breeding surgery, set up bioassays for urinary gonadotrophins and oestrogen (the female hormone) and concluded that the most important requirement in human reproduction was the development of a highly accurate method for timing ovulation in women, similar to the phenomenon of oestrus in animals.
His aim was to develop a chemical method for measuring the oestrogens in the urine and was given a position in the newly established Clinical Endocrinology Research Unit in the University of Edinburgh, later to be appointed its Assistant Director.
Notwithstanding Marrian's attempts at dissuading him from this project, Brown persisted and the essential problems were solved within a few months but a fully validated method was not published until 1955.
Using this new method of measurement, Brown confirmed the elegant patterns of oestrogen production throughout the menstrual cycle which had been shown previously using labour-intensive bioassays.
This work led to the award in 1952 of a Ph.D. from the University,[2] and the Lancet requested the privilege of publishing the results obtained during the menstrual cycle, conception, pregnancy, lactation and return to fertility.
During the 1970s he studied the effects of the intrauterine device on ovarian and menstrual function and was a member of the Melbourne In Vitro Fertilisation (IVF) team led by Prof Carl Wood.
With infertility due to anovulation now fully treatable, James Brown joined Professor Carl Wood's team which was developing in vitro fertilisation (IVF) for achieving pregnancy in women with occluded fallopian tubes.
This system uses urine, was simple enough for women to measure their hormone production at home, and could be used by assisted reproduction clinics to maintain daily control of their treatments.
As a final note, the quest for the equivalent of the phenomenon of oestrus in the human is now ended; it is contained in the concepts of the Basic Infertile Pattern (BIP), the oestrogen rise (ER) and the progesterone change (PC) which have come from the work of John and Lyn Billings.
He was the recipient of the Senior Organon Prize in 1978 and with Harvard Colleagues won the 1986 Prix Antoine Lacassagne from Paris for the most important contribution to the study of breast cancer for that year Brown retired from the University in 1985 and was accorded the title of Emeritus Professor.
He had established in 1962, a close working and personal relationship with Drs John and Lyn Billings who developed the concept of fertility recognition through the changes in cervical mucus secretion, forming the basis of Natural Family Planning.
Working with the Billings, the availability, simplicity and low cost of this facility enabled him to study literally hundreds of thousands of cycles in women in various stages of their reproductive lives and develop a theory of ovarian function which takes account of these findings.
Right up to the time of his death Brown continued to work on various scientific projects and was involved with the World Health Organization's Special Programme of Research in Human Reproduction.
Perhaps his professional life could best be summed up by a closing editorial comment made in 2003 in response to a letter he had published in Fertility and Sterility, the Journal of the American Society for Reproductive Medicine: "...In these days of hype, grossness and glitz, Dr Brown is a model of scientific practice who is even more imposing by the low profile that he has been able to keep over the last two decades.