53.—(1) In this regulation “temporary sign” means a sign placed on or near a road for the purpose of conveying to traffic—
(a)information about convenient routes to be followed on the occasion of—
(i)a sporting event;
(ii)an exhibition; or
(iii)any other public gathering,
which is in each case likely to attract a large volume of traffic;
(b)information about diversions or alternative traffic routes;
(c)information about the availability of new routes or destinations;
(d)information about changes in route numbers;
(e)warnings about, or information on how to avoid, any temporary hazards caused by—
(i)works being executed on or near a road;
(ii)adverse weather conditions or other natural causes;
(iii)the failure of street lighting or malfunction of or damage to any other apparatus, equipment or facility used in connection with the road or anything situated on or near or under it; or
(iv)damage to the road itself; or
(f)requests by the police for information in connection with road traffic accidents.
(2) A temporary sign—
(a)which conveys to traffic any information, warning, requirement, restriction or prohibition of a description which can be conveyed by a sign shown in a diagram in Schedules 1 to 12 (whether on its own or in conjunction or in combination with another such sign) shall be of the size, colour and type shown in that diagram;
(b)which does not fall within paragraph (a) (“a non-prescribed temporary sign”) shall be of such size, colour and type as is specified in paragraphs (3) to (6).
(3) The shape of a non-prescribed temporary sign shall be—
(a)rectangular but with the corners rounded; or
(b)as in sub-paragraph (a) with a rounded point at one end.
(4) A non-prescribed temporary sign shall be of a size appropriate to the circumstances in which it is placed and may incorporate—
(a)wording;
(b)numerals;
(c)arrows or chevrons;
(d)any appropriate symbol taken from any diagram in any Schedule; and
(e)the arms, badge or other device of a traffic authority, police authority or an organisation representative of road users.
(5) Every letter and numeral incorporated in a non-prescribed temporary sign other than any letter incorporated in the sign in accordance with paragraph (4)(e) shall be not less than 40 nor more than 350 millimetres in height, and every arrow so incorporated shall be not less than 250 nor more than 1000 millimetres in length.
(6) Every letter, numeral, arrow, chevron or symbol, other than a sign shown in a diagram in Schedules 1 to 5 when used as a symbol, incorporated in a non-prescribed temporary sign shall be—
(a)black on a background of white or of yellow;
(b)white on a blue background;
(c)blue on a white background;
(d)if the sign conveys information or warnings of the kind mentioned in paragraph (1)(e), white on a red background, except where it is placed on a motorway when it shall be black on a yellow background; or
(e)if the sign is a variable message sign, white, off-white or yellow on a black background or black on a yellow background, except when the sign is not in use when it shall display a plain black or grey face.