Is a condi tion which requires a change material to the risk of loss of coverage unreasonable?

In McKay v. Norwich Union, supra, p. 262, Street, J., observed that "an unreasonable condition is one which no sensible man would propose, expecting another man to accept it." And he went on to dismiss as unreasonable a condi tion which, of a row of tenament houses, required notice to the insurer and reconfirmation of coverage whenever a vacancy occurred, the insurer knowing from the start that, of such premises, tenancies are unpredictable. A condi tion, he thought, "manifestly more onerous than the statutory condition" of a "change material to the risk".