“The Purchaser hereby covenants with the Vendor for the benefit and protection of [No 30] and so as to bind so far as may be the land hereby conveyed into whosoever’s hands may come that he the Purchaser and the persons deriving title under him will not at any time hereafter: (a) permit the land hereby conveyed including the site of the existing dwelling house thereon to be used for the erection of more than one two-storey private dwelling house with all necessary outbuildings and garage for use in connection therewith (b) use or permit of suffer to be used the land hereby conveyed or any part thereof or any building or erection now or at any time hereafter erected thereon for any trade business or manufacture but will use the same as a private residence only.”