30E+WWhere all such maps and statements have been prepared for the whole of that area, the county council shall at one and the same time review the particulars contained in each of those maps and statements; and accordingly section 33 of the 1949 Act and Parts II to IV of Schedule 3 to the 1968 Act (periodical revision of maps and statements) shall apply as if the relevant date for the purposes of each of those maps and statements were the earliest of the relevant dates specified therein or such later date as, on the application of the county council, the Secretary of State may in any particular case direct.