(1)If any building, which abuts on a public street, is in the rear of the regular line of such street, the Board of Councilors may, whenever it is proposed-(a)to rebuild such building, or(b)to alter or repair such building in such manner as will involve the removal or re-erection of such building or portion thereof which abuts on such street and to an extent measured in cubic metre exceeding one-half of such building or portion thereof above the ground level,by an order, as respects the rebuilding, alteration or repair of such building or portion thereof, permit or require such building to be set forward to the regular line of such street.
