“(a)(i) Not without the previous written consent of the Vendor to alter the external plan or elevation of any building standing upon the Transferred Property nor without the like permission to erect any building thereon save those erected or in the course of erection at the date hereof … 6 (b) Not to use the Transferred Property at any time for any purposes other than that of a single private dwellinghouse and so that no trade business or manufacture whatsoever shall be carried on …”