(a) This section applies to a package store permit which was issued on or before April 1, 1971, and which was in good standing, not under suspension, and in actual operation and doing business on that date, unless temporarily prevented from operation by a natural disaster. This section does not apply to a permit if a change in the size or location of the licensed premises has occurred subsequent to April 1, 1971, or if after that date a change in ownership has occurred, by majority stock transfer or otherwise, except by devise or descent where the holder of the permit died on or after April 1, 1971.
(b) Notwithstanding any other provision of this code, the holder of a package store permit to which this section applies may continue to operate a package store on premises comprising a portion of a building if not later than November 28, 1971, he clearly defined the licensed premises by isolating it from the remainder of the building by the erection of a wall or screen so that the licensed premise is accessible from the remainder of the building only through a door or archway, eight feet or less in width, in the wall or screen. The door or archway must be kept closed during the hours in which it is not legal to sell liquor.