The most recent estimate of the common rat (Rattus norvegicus) population in England and Wales was a minimum of 5,240,000 individuals in England and 680,000 in Wales. These figures were established by a review that assessed the population and conservation status of all British mammals, published in 1995 and is also quoted in the UK Mammals Species Status and Population Trends report by the Tracking Mammals Partnership in 2005. A copy of the report can be found at the following weblink:
The only recent objective national survey of rat presence in England is within the English House Condition Survey (EHCS). The 2001 survey revealed that 0.3 per cent. of properties had rats indoors and 2.9 per cent. had rats present outside. A copy of the report can be found at the following weblink:
Under the Prevention of Damage by Pests Act 1949, local authorities are responsible for ensuring that their districts are kept, as far as is practicable, free of rats and mice. To enable them to do so, the Act empowers local authorities to serve a notice on landowners or occupiers requiring them to take such steps as may be specified in the notice to destroy rodents on their land.
The local authority has the power to enforce the duties of the owner or occupier and can use default powers to take those steps specified in a notice and recover any expenses reasonably incurred in doing so.