On 2011\10\30 18:29, Mortimer wrote:

Surely lack of Traffic Order means that the restriction cannot be
applied until the TO is in effect. Incorrect or inadequate sign-posting
means that the order is not legally enforceable. And I'd expect the
signs at *all* banned turns to be consistent, and not to conform to
different standards based on what, for most drivers, is a technicality.
There is no harm in telling people essentially the same thing in more
than one way (green arrow and no turn left/right signs) - there are no
prizes for being minimalist and reducing the level of signage. If
"redundant" signs reduce accidents and maybe even save lives, they are a
good thing.

Maybe it's a power saving measure... some sustainability guru has worked
out how much power is used by having a white on blue arrow lit up all
night, when traffic is banned from moving half the time anyway.