In 1953 the Myxoma virus killed a massive 99% of the British rabbit population (5). A level of resistance is now apparent (4), and although the virus is still present in the population, the mortality caused has fallen substantially (5). Rabbit haemorrhagic disease (RHD) was first identified in British rabbits in 1994, and the combined effect of myxomatosis (the disease caused by the Myxoma virus) and RHD is as yet unknown (5). Rabbits are serious agricultural pests and their populations are controlled by shooting, trapping and exclusion in many areas. They can pose serious threats to sensitive habitats, yet conversely, rabbit grazing is essential for the maintenance of other threatened habitats such as calcareous grasslands (5).