The relationship between planning policy and planning law is complex. Arguably law should be the servant of policy; yet policy cannot be translated into practice without law, and while in most instances law merely provides the formal framework within which decisions are taken, there are occasions when law influences policy to a considerable extent. The historic general philosophy of regulation amongst planners in the United Kingdom in the 20th century has been to ensure the prevention of urban sprawl, the eradication of nuisances and the preservation of amenity. The Secretary of State also accepted his argument (that to grant permission without a properly conducted survey of the area, and without a thorough investigation of alternative sites was unacceptable) was incorrect in that it conflicted with the draft of the revision of Planning Policy Guidance (PPG) 6 then current. In coming to a decision on an application an authority will be much guided by its 'development plan'.