Just a thought:
About a year before lockdown, my Borough started reducing NSLs to 50mph limits, and shortening the existing 40mph stretches of road. They have consistently lowered limits throughout the Borough to the point that what were NSLs are now 30 and 40mph limits, along with the introduction of 20mph limits in some areas. (Not just school areas.) Along with the introduction of mobile and fixed cameras, are more people speeding, or are more getting caught out by these limit changes? I don't believe mine is the only Borough doing this.
FWIW: HS2 work has apparently necessitated that some of the roads local to me now have been reduced from NSLs and 40 limits, to 20 limits with no reasonable excuse, as all the new roads and Vehicles Emerging areas have had traffic lights installed.