"It is to be noticed in the present case that the benefit of the covenant is not intended to pass to a purchaser without express assignment. It is not necessary for us to express any opinion as to what would be the effect of a sale of part of the settled property with an express assignment of the covenant; but, if such a purchaser could enforce the covenant, it could only be for so long as some successor in title of the original covenantee retained some part of the settled property, since such a person alone can form the requisite opinion. For these reasons the appeal must be allowed. The appellant is entitled to the injunction which he seeks subject to two limitations. In the first place the injunction must be limited to fried fish ... because the opinion of the appellant as to the nuisance was confined to fried fish, and secondly, the period of the injunction must be confined to so long as the appellant or some successor in title of the original vendor retains unsold any part of the settled property for the benefit of which the covenant was imposed." (Emphasis added.)