The powers of the undertakers for the compulsory acquisition of the lands and rights which they are authorised to acquire by this Part of this Act shall not be exercised after the expiration of five years from the passing of this Act.

The powers of the undertakers for the compulsory acquisition of the said lands and rights shall, for the purposes of this section, be deemed to have been exercised if notice to treat has been served in respect of those lands and rights.