From the case summary: -
"The blue directional arrow indicates for vehicles to turn left into Howland Street to avoid the restriction."
What tosh!
The restriction is not 24x7, but this sign on the traffic lights is, being a mandatory 24x7 instruction. So why are they serving PCNs for the route restriction when the PCN recipient has already passed a mandatory left turn sign ? Basically, the signage at this location is flawed.