The Traffic Signs Regulations and General Directions 1994

Signs to be placed only on specified types of road

14.—(1) The signs shown in diagrams 823, 824, 825, 868, 868.1, 872, 873, 874, 875 and 876 may be placed only on or near—

(a) a motorway when the colour of the background of the sign is blue;

(b) a primary route when the colour of the background of the sign is green; or

(c) a non-primary route when the colour of the background of the sign is white.

(2) The sign shown in diagram 877 may be placed only on or near—

(a) a primary route when the colour of the background of the sign is green; or

(b) a non-primary route when the colour of the background of the sign is white.