The mutation responsible for most cases of genetic haemochromatosis in Europe (HFE C282Y) appears to have been originated as a unique event on a chromosome carrying HLA-A3 and -B7. It is often described as a "Celtic mutation"--originating in a Celtic population in central Europe and spreading west and north by population movement. It has also been suggested that Viking migrations were largely responsible for the distribution of this mutation. Two, initial estimates of the age of the mutation are compatible with either of these suggestions. Here we examine the evidence about HFE C282Y frequencies, extended haplotypes involving HLA-A and -B alleles, the validity of calculations of mutation age, selective advantage and current views on the relative importance of "demic-diffusion" (population migration) and "adoption-diffusion" (cultural change) in the neolithic transition in Europe and since then. We conclude that the HFE C282Y mutation occurred in mainland Europe before 4,000 BC.