Despite enjoying a population boom, rats limped in at third on 9%. There is no official record of the number of rats in Britain, but in 2002 it was estimated at 60m - one for each person. As well as carrying salmonella and Wiel's disease, rats will readily feed on humans if we will hold still for long enough. There are numerous reported cases of attacks on people in the past few years, particularly babies, who were attacked by rats as they slept in their cribs. Arrrggghhh!