Before the Commencement of any Improvements sanctioned in manner aforesaid the Landowner shall deliver to the Commissioners a detailed Specification thereof, and in the Case of Buildings, and also in any other Case where the same shall be required by the Commissioners, a detailed Plan or Drawing: Provided that when it is not intended to complete the Improvements within One Year from the Date of the provisional or other sanctioning Order, the Specification and Plan or Drawing first delivered may comprise so much only as it is intended to complete within One Year from the said Date, so, however, that for the Works of each successive Year such Specification and Plan or Drawing as aforesaid be always delivered in advance.