1) Legal Authorities.
MacLeod v Hamilton 1965 S.L.T 305
If signs to indicate the effect of a "No Waiting" order have not been erected, or signs have been erected not conforming to s.64 of the RTRA 1984 and TSRGD 2002 (SI 2002/3113), no offence against the "No Waiting" order is committed.
Hassan v DPP  R.T.R. 209, Divisional Court
The absence of a sign specifying the prescribed hours of restricted parking in a road marked with a single yellow line is fatal to a successful prosecution for a no waiting offence.
Davies v Heatley  R.T.R 145
Because by s.64(2) of the Road Traffic Regulation Act 1984 traffic signs shall be of the size, colour and type prescribed by regulation, if a sign the contravention of which is an offence contrary to s.36 is not as prescribed by the regulation, no offence is committed if the sign is contravened, even if the sign is clearly recognisable to a reasonable man as a sign of that kind.