What no-one seems to have looked at so far is Haringey's authorisation from the DfT for its temporary parking suspension signage. Surprising theough it might seem, Haringey obtained its authorisation back in 2011 and appears never to have updated it. Here it is:
https://assets.dft.gov.uk/trafficauths/case-2964.pdfYou will note at para 1(a) that it states specifically that the year should be omitted from the suspension notice. And the sign as photographed clearly shows the year as "23". This was common rubric back at that time and a lot of councils have updated their authorisations to provide that the year may or may not be shown. However it seems that Haringey have been lazy and a) have not updated the auth and b) simply copied RBKC's diagram as you can see from the authority name on the bottom. However note that at 1(c) the authority name may be varied or omitted so this is not evidence of non-compliance in itself.
I never understood why the original batch of authorisations provided for omission of the year but the fact is that they did and if the authorisation specifically states that the year should be omitted and it is in fact included, this looks like a non-compliant sign to me. As a secondary matter, I can't tell from the photos as posted whether the suspension signs have the side-wings with the appropriate verbiage but if not, this would be additional evidence of non-compliance.
One for Mr Mustard to consider in drafting up a formal appeal but it must be one more football lined up in front of the goalmouth - or at least an indirect free kick