Commentary on Sections Part 3: Planning Control. Section 24: Development requiring planning permission
This section re-enacts the requirement for planning permission to be sought for developing land. Permission is not required to return to a former land use after planning permission which is time bound expires.  Development orders can grant planning permission without applications being required.  Where an enforcement notice has been issued permission is not required for the use of the land for any purpose it could have been legally used for if the development which is being enforced against had not been carried out.