I agree with
@John_S that the signage can be challenged as inadequate.
If you're driving south along Leopold Road and turn right into Lake Street, you're forced to the left of the traffic islands. There's a small yellow sign on the left with tiny writing pointing to the right. That sign will be out of date and really doesn't give any advance notice that you shouldn't be turning right.
As you turn, the signs about the Pedestrian and Cycle Zone (diagram 618.3C) are so far from your line of sight as to be in your peripheral vision. To make the turn you position yourself opposite the centre-line of Lake Street and wait for a gap in the oncoming traffic. Paragraph 4.5.3 of Chapter 1 of the Traffic Signs Manual states:
For safety reasons, drivers should not need to divert their eyes more than ten degrees away from the road ahead, meaning that the message on a sign must be fully absorbed before a driver reaches that position... The effect of the line of approach of a vehicle has to be considered separately as part of the design process to ensure the satisfactory performance of the sign
The problem which Merton have created here is that they have restricted Lake Street from its junction with Leopold Road, but there is a wide splay at its entrance. The regulations require the placing of the diagram 618.3C signs at the junction, i.e. where they are. But this makes them unreadable to motorists approaching from either direction. What Merton could have done, given the width of the splay, was to put a traffic island in the middle of the junction, on which they could have put a diagram 618.3C. This would at least be in the line of sight of traffic from the north.
For both directions they should also have proper map-type advance notice signs, not the yellow signs which are meant to be temporary (maximum of 6 months). Map-type advance direction signs show the road ahead as a vertical black line with a stub to the left or right, beyond which are a "flying motorcycle" roundel and the days and times when the restrictions apply. That gives approaching motorists notice of what's coming ahead. This sign might require special permission from DfT for the multiple days and times, but as Merton have already obtained special permission for their signs, there should be no issue about obtaining further permission.
Given the poor legibility of the diagram 618.3C signs from the line of sight of approaching motorists, map-type advance notice signs really are required to provide adequate signage. In their absence, no contravention occurred; see
James v. Cavey [1967] 2 QB 676. The following excerpt is from the judgment by Lord Justice Winn in the Court of Appeal (so an important precedent):
The short answer in my view which requires that this appeal should be allowed is that the local authority here did not take such steps as they were required to take under that regulation. They did not take steps which clearly could have been taken and which clearly would have been practicable to cause adequate information to be given to persons using the road by the signs which they erected.
