The production of cereals in the United Kingdom has increased steadily over recent years from 12.6 million tonnes in 1964 to 21.8 million tonnes in 1982. During this period, the United Kingdom's accession to the E.E.C. in 1973 caused a reverse in the milling industry's policy of including only a small proportion of home-grown wheat with imported wheat in breadmaking grists. Home-grown wheat is now the major constituent of mass produced bread. Since the passing of the Plant Varieties Rights Act in 1964, plant breeders have been able to collect royalties on the sale of seed of their varieties; this led within a decade to a large number of high yielding varieties on offer to the farmer. Thus during the period of adjustment to home-grown wheat after 1973, the milling industry had to select from a wide range of varieties of different milling and baking qualities. Selection was aided by the offer of a `premium' (extra payment) for wheat of the right variety. The millers' problem then was to be able to check that the wheat received was of the variety claimed by the supplier. Investigations of the heterogeneity of gliadins by electrophoresis had been conducted by several workers, but a refined procedure was developed that used starch gel electrophoresis that was able to distinguish most varieties of wheat grown in France and the E.E.C. Different electrophoretic patterns were obtained from individual grains of different varieties: grains of the same variety gave similar patterns irrespective of growth environment. Subsequent developments of variety identification by electrophoresis have improved the resolution and time of analysis. Use of electrophoresis to check the varietal composition of grain being supplied to a British miller revealed that contracts that specified varietal content were usually, but not always, complied with. It was found that the miller was able to seek financial reimbursement from his supplier to compensate for the poorer grade of wheat received in about one in eight deliveries from France; and in about one in seven deliveries from the British farmer. Farmers have now adjusted to growing, storing and supplying varieties separately, such that the current frequency of erroneous grain delivery is about one in 50. The impact of variety identification by electrophoresis in barley trading has been less than in wheat trading. This is partly because it is sometimes possible to verify a purchase through examination of grain morphology, and partly because the alternative electrophoretic analysis is often impractical, because of frequently large numbers of barley varieties carrying identical hordein proteins.