The status of an NMGD varies considerably from one to another. For example:
Senior officials in HM Revenue and Customs work closely with cabinet ministers. Its key policies are set each year in the Finance Act. However, neither ministers nor parliament can interfere in day-to-day taxation decisions.
A number of NMGDs are highly independent bodies; for example the Charity Commission, Ofsted and economic regulators such as the Competition and Markets Authority or the Postal Services Commission. These bodies are "creatures of statute": – that is they implement legislation which they have no power to change. Their political independence is assured by providing that they have the status of government departments, but are accountable only to parliament and the courts. Their budgets are usually set by the Treasury, not by the department which set them up, and they are often funded by licence fees paid by the industries which they regulate.
The Food Standards Agency is an NMGD which was created by merging two large parts of the Departments of Health and what was then the Ministry of Agriculture, Fisheries and Food. The aim was to reassure the public (after the BSE/vCJD crisis) that decisions about food safety would in future be taken by an independent body free of political control. Because the FSA was designed to take politics out of food safety, it does not seek ministerial approval for its actions, even when negotiating and agreeing to European legislation on behalf of the UK.