Clive D. W. Feather wrote on 30 October 2011 08:20:10 ...
In , Basil Jet
wrote:
At the crossroads of Exhibition Road and Cromwell Road SW7, traffic
approaching from three directions is now banned from turning left or
right. This is signified by the green light being a forward arrow.
[...]
I am doubtful that you could be prosecuted for turning when the
temporary signs are gone and the green arrow light is all that remains.

The green arrow only gives you authority to move in that direction.

http://www.legislation.gov.uk/uksi/2...ading/light-si
gnals-and-warning-lights/made

and scroll down to paragraph 36.

There are some junctions where traffic gets a green arrow in one
direction first, then later a full green. In those cases no other signs
are needed or would be appropriate.

At Exhibition Road I agree that it would be helpful to have a
white-on-blue arrow as well, but maybe the current restriction is temporary.
--
Richard J.
(to email me, swap 'uk' and 'yon' in address)