4.—(1) The prohibitions specified in article 3 above shall apply only during such times and to such extent as shall from time to time be indicated by traffic signs specified by regulations or authorised under section 64 of the Road Traffic Regulation Act 1984.
(2) The prohibitions specified in article 3 above shall not apply in respect of—
(i)any vehicle being used for the purpose of those works, or for fire brigade, ambulance or police purposes, or
(ii)anything done with the permission or at the direction of a police constable in uniform or a traffic warden.