On 19/12/2014 15:58, Jethro_uk wrote:

It is a result of a DfT guideline that speed limits should not reduce by
more than 20mph in one step, so you get 60mph / 40mph / 30mph / 40mph /
60 mph and 70mph / 50mph / 30mph / 50mph / 70mph wherever that guideline
has been implemented.

Guideline, but not law clearly. Theres an NSL to 30mph transition a
couple of miles from me.


There are lots of them around here.
I can probably find a few hundred without much effort.