32.—(1) The sign shown in diagram 878 or 879 may be placed only in an area or along a route where enforcement cameras are from time to time in use.
(2) The sign shown in diagram 880 may be placed only—
(a)on or near a road on which there is provided a system of carriageway lighting furnished by means of lamps placed not more than 183 metres apart in England and Wales or 185 metres apart in Scotland and which is subject to a speed limit of 30 mph; and
(b)not more than one kilometre from a site at which an enforcement camera has been installed and is from time to time in use, and
not more than one such sign may be so placed on each approach to that site.