The signs at each end of the restricted area are unlawful because they all have a blue sign "term time only", but do not tell you what the start and end dates are. In contrast, signs at entrances to parking zones where special event day restrictions are in place, like near football grounds, must state the next event date.
Appeals have been won on this, so don't cough-up, but instead submit Hippocrates draft for representations. Post their response when you get it.