1Until the repeal of Part II of the principal Act and, where applicable, section 25 of the [1963 c. 33.] London Government Act 1963 as respects any district (whether the whole or part of the area of a local planning authority), proposals for any alterations or additions to a development plan in force in the area consisting of or comprising that district shall not without the approval of the Minister be submitted to him under section 6 of the principal Act or under section 26 of the said Act of 1963.