Nothing in this Act shall affect the powers and duties of the County Council of Middlesex with respect to main sewers and sewage disposal under the Middlesex County Council Act, 1931, or impose on local authorities of that county any obligations with respect to sewers or sewage disposal from which they were relieved by the said Act:
Provided that, on the application of the county council, the Minister may by order amend the said Act by making therein such adaptations and modifications as appear to him to be necessary in consequence of the amendments made by this Act in the general law relating to public health, and, in particular, by applying to the county council, by way of substitution but with any necessary adaptation, such of the provisions of this Act as appear to him to correspond to any provisions of the Public Health Acts, 1875 to 1932, which were applied to the council by the said local Act.