This section applies if the Secretary of State thinks that the condition in subsection (2) or (3) is met.
The condition is that—
since the time when a national policy statement was first published or (if later) last reviewed, there has been a significant change in any circumstances on the basis of which any of the policy set out in the statement was decided,
the change was not anticipated at that time, and
if the change had been anticipated at that time, any of the policy set out in the statement would have been materially different.
The condition is that—
since the time when part of a national policy statement ("the relevant part") was first published or (if later) last reviewed, there has been a significant change in any circumstances on the basis of which any of the policy set out in the relevant part was decided,
the change was not anticipated at that time, and
if the change had been anticipated at that time, any of the policy set out in the relevant part would have been materially different.
The Secretary of State may suspend the operation of all or any part of the national policy statement until a review of the statement or the relevant part has been completed.
If the Secretary of State does so, the designation as a national policy statement of the statement or (as the case may be) the part of the statement that has been suspended is treated as having been withdrawn until the day on which the Secretary of State complies with section 6(5) in relation to the review.