3Where after 1st July 1948—
(a)any buildings or works have been erected or constructed, or any use of land has been instituted, and
(b)any condition imposed under Part III of this Act, limiting the period for which those buildings or works may be retained, or that use may be continued, has effect in relation to those buildings or works or that use,
this Schedule shall not operate except as respects the period specified in that condition.