1934), with '30' in black letters on a white disc surrounded by a red ring, to indicate it is an order sign. The 30 mph sign was accompanied by its 'derestriction' sign, a white disc with a diagonal black band bisecting it, which marked the end of the restriction. Neither of these signs required separate information plates. The 1934 RTA&R also clarified direction and distance signage, which remained in that form until 1964. All signs were mounted on posts painted in black and white stripes, and their reverse sides were finished black, green, or more rarely (usually after repainting) white. The 'HALT' plate was unique in being T-shaped; orders were mainly landscape and warnings always portrait. Sizes were strictly prescribed, the warning plate being with the surmounting triangle equal. As part of its anti-invasion preparations during World War II, the British government instructed all navigational signposts and railway station signs to be removed, so as not to aid potential enemy ground movements. After the war ended, larger motoring associations embarked upon a programme to erect temporary road signs. These temporary signs, which were not required to conform to the standardisation laid down by the government, usually displayed the motoring association’s logo and colour-scheme. Some road signs were subject to minor modification, mainly in the early post-World War II years. For instance, 'SCHOOL' became a schoolboy and girl marching off a kerb, 'CHILDREN' a boy and girl playing handball on a kerb's edge. A train 'CROSSING NO GATES' was given a more toy-like locomotive. Meanwhile, the triangle was inverted for 'HALT' and 'SLOW', while 'NO ENTRY' became a combination sign - a red disc bisected by a horizontal white rectangle bearing the lettering. Orders were now black on white, save for 'NO WAITING', which was black on yellow in a red ring. Some of these changes were part of an attempt to reflect European standards. Early road signs were usually cast iron, but this was increasingly displaced by cast aluminium in the 1930s. Cast signs were designed to be maintained by being repainted with the raised lettering and symbol easily picked out by an untrained hand. This sort of sign was sometimes given an element of night use by the inclusion of glass reflectors. An alternative to casting and painting was vitreous enamelled sheet iron or steel. In the 1950s cast signs were quickly displaced by sheet metal (usually aluminium) coated