Paragraph 4

for naval, military or air force purposes;

for civil aviation purposes under the powers conferred by section 19 or 23 of the M1Civil Aviation Act 1949 or any enactment replaced thereby:

shall exclude the application of section 1 of this Act to an obligation falling within sub-paragraph (i) above, and not created or imposed in connection with the use of any land as an aerodrome, only so long as the obligation is enforceable by or on behalf of the Crown; and

shall exclude the application of section 1 of this Act to an obligation falling within sub-paragraph (ii) above, or created or imposed in connection with the use of any land as an aerodrome, only so long as the obligation is enforceable by or on behalf of the Crown or any public or international authority.