Directions made under earlier general development orders, such as the Town and Country Planning General Development Order 1977 (TCPGDO 1977), SI 1977/289, are given continued effect by virtue of sections 17(2)(b) and 23 of the Interpretation Act 1978. The effect of these provisions is that an Article 4 direction made pursuant to the TCPGDO 1977, SI 1977/289, and made after 1 January 1979 remains valid and in force (unless modified or cancelled) and has effect 'as if made' pursuant to the Town and Country Planning (General Permitted Development) (England) Order 2015 (GPDO 2015), SI 2015/596. The Town and Country Planning General Development Order 1988, SI 1988/1813 revoked the TCPGDO 1977, SI 1977/289. Subsequent permitted development orders, including the GPDO 2015,