The use of laboratory animals in scientific procedures in the United Kingdom is highly regulated and, in the case of non-human primates (NHPs), it is intended that they are only used in scientific studies when no other animal species would provide a suitable model and when no alternative methods are available. Additionally, there must be a high likelihood that the research will lead to important medical advances. The number of NHPs used in scientific procedures each year in the UK are relatively small (in 2010 less than 0.1% of the 3.6 million animals used) however, it is thought that the welfare cost to NHPs in a laboratory environment may be greater than for other animals because of their sentience and social nature. In 2006, the report of a working group chaired by Sir David Weatherall, recommended that the major funding bodies of non-human primate research in the UK should systematically review the outcome of all of their research using NHPs over a ten-year period.