In message , at 16:20:12 on Mon, 9 Jul
2018, John Williamson remarked:
Perhaps you could name a borough that you think is 100% 20mph and I'll
point out the roads in it which aren't.

I can't be bothered checking which ones, but while a few claim to be
completely 20mph, they all have roads which are part of the national
trunk network in them, which are at least 30mph,

And being trunk roads are congested enough that 8mph is a more realistic
figure.

as they can't set the limits on those roads, due to them being under
DFT control.

--
Roland Perry