This Act (including the amendments and repeals made by it) shall not have effect in relation to any compulsory acquisition in pursuance of a notice to treat served before the commencement of this Act or served in the exercise of powers conferred by Part II of the Requisitioned Land and War Works Act, 1945 ; nor in relation to any sale of an interest in land by agreement in pursuance of a contract made before the commencement of this Act.