63.—A house shall for the purposes of this Act be deemed to be overcrowded at any time when the number of persons ordinarily sleeping in the house and the number of rooms therein either—

(a) are such that any two of those persons, being persons of ten years of age or more of opposite sexes and not being persons living together as husband and wife, must sleep in the same room, or

(b) are such that the free air space in any room used as a sleeping apartment, for any person is less than four hundred cubic feet (the height of the room, if it exceeds eight feet, being taken to be eight feet, for the purpose of calculating free air space),

and “overcrowding” shall be construed accordingly.