Any listed building consent granted after the commencement of this section shall be granted subject to a condition that works permitted by that consent shall be commenced within such period as the planning authority may specify in the consent.

If no time limit is specified in any grant of listed building consent under subsection (1) above, the grant shall be deemed to have been made subject to a condition that works in terms thereof shall be commenced with 5 years from the date of the grant.

Any grant of listed building consent made prior to 1st January 1980 which does not contain such a condition as is mentioned in subsection (1) above shall be deemed to have been granted subject to a condition that works in terms thereof shall be commenced within 3 years of the commencement of this section.

Any grant of listed building consent made on or after 1st January 1980 but before the commencement of this section which does not contain such a condition as is mentioned in subsection (1) above shall be deemed to have been made subject to a condition that works in terms thereof shall be commenced within 5 years of the commencement of this section.]

Nothing in this section applies to any consent to the retention of works granted under section 53(2A) of this Act.