37.—(1) The sign shown in diagram 790 or 7014—
(a)may be placed only in connection with works involving—
(i)an alteration in the layout of the carriageway of a road or level crossing; or
(ii)the placing, removal or alteration of traffic signs on or near a road or at a level crossing; and
(b)may be retained not later than the end of the period of 3 months beginning with completion of those works.
(2) The sign shown in diagram 7032—
(a)may be placed only to indicate the point at which a recently imposed speed limit of 30 mph begins on a road—
(i)on which there is a system of street or carriageway lighting furnished by lamps lit by electricity placed not more than 183 metres apart in England and Wales or not more than 185 metres apart in Scotland; and
(ii)which had previously been subject to a higher speed limit;
(b)shall be placed as near as practicable to that point;
(c)shall not be placed unless that point could not otherwise be indicated in accordance with these Directions;
(d)may be placed only during the period of 6 months beginning with the day on which the 30 mph speed limit comes into force; and
(e)shall not be retained after the end of that period.