Our data consists of information on all the farms in the UK listed in the 2000 agricultural census [see http://www.defra.gov. uk/footandmouth/cases/index.htm ]. There were a total of 134,986 farms listed in that dataset and uniquely identified by their County/Parish/Holding (CPH) number. Their spatial coordinates are provided together with the number of animals by species within each farm. A partition of all GB farms according to the animal types represented is shown in Figure 1a . Their geographical distribution is represented in Figure 1b as the number of farms per 565 km. Notice the high density areas in the North West (Cumbria), South West (Devon), Wales and Scotland where the main epidemic foci developed. There is also an area of high density in the Shetland Islands corresponding to very small crofter smallholdings. Figure 1c and d show the numbers of sheep and cattle kept per 565 km square.