[R (on the application of Herron and others) v Parking Adjudicator [2011] EWCA Civ 905, [2011] All ER (D) 253 (Jul)
Regulation 4 of the Traffic Signs Regulations and General Directions 2002, SI 2002/3113, did not require that every part of every street was signed in the manner it specified. The fact that there were road signs regulating parking, and in particular those at pedestrian crossings, that were not referred to in reg 4 rendered it impossible to read it as requiring the specified signage in every part of every road.
Even where a statute was clear in imposing a duty, and did so in terms that were apparently mandatory, it would not necessarily be interpreted as invalidating steps taken by a public authority that were not in strict conformity with the duty. A controlled parking zone (CPZ) was to be treated as valid unless it could be said that in substance, because of the failure adequately to inform the road user, it could not be considered to be a valid CPZ.