Having done some research here is my reply.
I note from your comments that you state all signage is compliant with The Traffic Signs Regulations and General Directions 2002, this is clearly not the case.
Part 1, Section 1, Item 4 - Interpretation - general states that a "controlled parking zone" means either -
(a) an area -
(i) in which, except where parking places have been provided, every road has been marked with one or more of the road markings shown in diagrams 1017, 1018.1, 1019 and 1020.1; and
(ii) into which each entrance for vehicular traffic has been indicated by