Three further Acts related to planning are associated with this primary act: The Planning (Listed Buildings and Conservation Areas) Act 1990, the Planning (Hazardous Substances) Act 1990, and the Planning (Consequential Provisions) Act 1990. These four Acts are referred to as the Planning Acts. Almost immediately after parliament passed these Acts, the government had further thoughts on the control of land development, which led to the Planning and Compensation Act 1991, which made important alterations to many of the Planning Acts provisions.