(1) A traffic-related item of a kind mentioned in these Rules has effect for the Rules if—
(a) the item is on a road, or on a vehicle on a road; and
(b) the item complies substantially with the Rules.
(2) A traffic-related item is taken to comply substantially with these Rules unless the contrary is proved.
1 "Road" includes a road related area—see rule 11(2).
2 Rule 322(1) and (2) explain the meaning of a traffic control device on a road.