An application for planning permission may relate to buildings or works constructed or carried out, or a use of land instituted, before the date of the application, whether—
the buildings or works were constructed or earned out, or the use instituted, without planning permission or in accordance with planning permission granted for a limited period; or
the application is for permission to retain the buildings or works, or continue the use of the land, without complying with some condition subject to which a previous planning permission was granted.
Any planning permission granted in accordance with subsection (2) of this section may be granted so as to take effect from the date on which the buildings or works were constructed or carried out, or the use was instituted, or (in the case of buildings or works constructed or a use instituted in accordance with planning permission granted for a limited period) so as to take effect from the end of that period, as the case may be.