What was the effect on existing laws applying to major ports or aerodromes after this amendment?
After the amendment, the Constitution (Twenty-sixth Amendment) Act, 1971, allowed the President to issue public notifications directing that as from a specified date:

(a) any law made by Parliament or by the Legislature of a State shall not apply to any major port or aerodrome or shall apply thereto subject to such exceptions or modifications as may be specified in the notification, or

(b) any existing law shall cease to have effect in any major port or aerodrome except as respects things done or omitted to be done before the said date, or shall in its application to such port or aerodrome have effect subject to such exceptions or modifications as may be specified in the notification.