In United Kingdom planning law, a unitary development plan (UDP) is an old-style development plan prepared by a metropolitan district and some unitary local authorities that contains policies equivalent to those in both a structure plan and a local plan. By virtue of specific transitional provisions, these plans will continue to operate for a time after the commencement of the new development plan system.
The unitary development plan is used at all stages of production and is reliant on criteria-based policies. Often contentious sites are proposed, which may generate significant opposition to the proposal. The existing system of UDPs makes it very difficult to provide a clearer framework.