Wales and new 20mph speed limit clarification

So just to clarify..
There seems to be some significant confusion
here in Wales ahead of tomorrow's Speed Limit
change and so, I thought I would help by briefly
explaining how the change works so that there
can be no confusion:
Any roads that were previously 30 will now be 20
apart from the roads that aren't going to be 20,
which will still remain as 30. When you see street
lights you have to assume that the roads will be
20 even if the signs still say 30 because despite
the signs saving 30, the roads could be 20, apart
from, of course, the roads (as explained above)
which will remain 30 despite them being 20. It's
also important to remember that there will still
be a number of roads which despite them having
streetlights will not be 20, and in these cases
they could be 30, 40, 50, 60 or even 70, however,
always bear in mind that even if the signs on
these roads still state 30 they could, of course, be
20 unless they are one of the roads that have
been designated 30, in which case the 20
restriction will not apply.
I trust that clarifies. It's really not difficult.