Restrictions on the obscuration of certain obligatory lamps and reflectorsE+W+S
19. Every vehicle shall be so constructed that at least part of the apparent surface of any–
(a)front and rear position lamp,
(b)front and rear direction indicator, and
(c)rear retro reflector,
which is required by these Regulations to be fitted to a vehicle is visible when the vehicle is viewed from any point directly in front of or behind the lamp or reflector, as appropriate, when every door, tailgate, boot lid, engine cover, cab or other movable part of the vehicle is in a fixed open position.