During the interwar period, Cambridge became the centre of scientific cereal breeding in Britain. Largely based within university departments, much of this work has appeared remote or even hostile to the agricultural community at large. However, one Cambridge institution, the National Institute of Agricultural Botany (NIAB) did place the concerns of farmers and commercial breeders at the centre of its activities. Founded in 1919 by large private and public donations, NIAB came to adopt numerous responsibilities; housing the Official Seed Testing Station for England and Wales, multiplying and selling ‘pedigree’ seed, monitoring the activities of commercial breeders and farmers and much more besides. However, what really came to dominate the institute’s agenda was the trialling of old and new varieties under field conditions. This was a highly practical problem requiring sensitivity to differential levels of husbandry, the peculiar demands of local conditions and no small amount of cooperation with farmers (small and large) in the generation and collation of data. What is more, these practical investigations had implications for the theory of genetics.

Agricultural problems have often informed the theory and practice of science. For instance, the improving of plant varieties has been attempted from within many scientific disciplines; plant pathology, agricultural chemistry, plant physiology, agronomy and so on. I have chosen to consider the perspective of the agricultural geneticist for two main reasons. Firstly, it is already abundantly clear that the agricultural context provided important institutional and intellectual terrain for the early history of genetics. There is therefore, an existing historiography in which to situate my work. Secondly, histories of British genetics rarely extend into the interwar period, other than to discuss elements of population genetics. This paper affords an opportunity to consider the development of genetics in a period and context that has been otherwise overlooked. The primary object of the paper will be to reconstruct how Cambridge geneticists attempted to breed better varieties and subsequently, how any purported improvement was assessed by NIAB. The trials conducted by the latter exposed varieties to be far more variable than allowed by proponents of a naïve Mendelism.