In all cases where a district boundary divides a lot in one ownership on the date of the enactment of this regulation, and more than 50% of the area of such lot lies in the less restrictive district, the requirements prescribed by this regulation for the less restrictive district may be extended by the Commission to such portion of the more restrictive portion of said lot which lies within 50 feet of such district boundary. For purpose of this section, the more restrictive district shall be deemed that district subject to regulations which prohibit the use intended to be made of said lot, or which require higher standards with respect to density, coverage, yards, screening, landscaping, lighting, parking, loading, and similar requirements.