This paper examines the fate of alleles and changes of genetic diversity in old (ca 1930s) versus more modern (ca 1990s) UK bread wheat varieties using 14 mapped DNA microsatellite (simple sequence repeat, SSR) loci and morphological markers. The allelic constitution of varieties belonging to three time periods (early, intermediate, late) was determined. While at certain loci one or more SSR alleles were gained between early and late periods, at others the allelic representation remained constant, although a shift in allelic frequencies could sometimes be detected. No locus showed a clear, net loss in the total number of alleles over the time period. In a further group of loci, there was neither clear gain nor loss, but rather a dynamic flux of alleles. A comparison of the allelic constitution of the UK variety set with a larger genetic pool (non-UK varieties) showed that some loci were rather similar in allelic constitution, while others possessed additional diversity. Certain SSR alleles appeared to be associated with old or modern varieties, possibly indicating associations with chromosome regions under selection pressure. The same exercise was conducted on the basis of 14 of the morphological characteristics recorded in the course of distinctness, uniformity and stability testing of varieties. Overall, this analysis generated a similar picture of changes in diversity to that obtained from the microsatellite data.