If it appears to the local planning authority that the amenity of a part of their area, or of an adjoining area, is adversely affected by the condition of land in their area, they may serve on the owner and occupier of the land a notice under this section.

The notice shall require such steps for remedying the condition of the land as may be specified in the notice to be taken within such period as may be so specified.

Subject to the following provisions of this Chapter, the notice shall take effect at the end of such period as may be specified in the notice.

That period shall not be less than 28 days after the service of the notice.