This paper has presented a statistical analysis of the spatiotemporal evolution of the 2001 foot and mouth outbreak in GB. Qualitatively, the results agree with those obtained by Keeling et al. [5] in identifying cattle as being the key species in the 2001 epidemic. Using the interaction model conditioned on 23 rd February with time varying cattle infectivity, we estimated that 88% of IPs between 23 rd Feb-31 st March were infected by cattle and only 12% by sheep. Sheep-to-sheep transmission only accounts for 3.1% of IPs in that period. After 31 st March (when we estimated that cattle infectivity increased slightly, see Table 2 ) Allowing for non-random mixing between species indicates contacts between farms are assortative on the basis of species composition of the farm; i.e. like species mix with like. This agrees with intuition about the nature of farming practices (e.g. sharing of personnel and equipment is likely to be more common if 2 farms have the same livestock species). The implications of the moderate degree of assortativity we found for control measures remains to be explored.