(2) Unless within seven years after the passing of this Act the said Board of Governors has erected buildings as approved by the Minister of Education on the said land for the purposes of the Hamilton High School, the Hamilton Domain Board may, by notice in writing delivered to the Chairman of such Board of Governors, resume possession of such land, and the land shall at the expiration of three months after the service of the said notice revert to the Crown and be subject to the provisions of the Public Reserves and Domains Act 1908, and the Hamilton Domains Act 1911.