Thank you for this - just a little further clarification please.
Are we saying that:
if the exit is not clear, one should not proceed past the signal stop line even though the signal is green, or,
if the exit is not clear, one can pass the signal stop line but not proceed further than the edge of the yellow hatched box some six to eight metres further into the junction?
How are the edges of a box junction defined?
Is it the the area enclosed by the stop signal lines, or,
is it the area enclosed by the yellow box itself?
If the latter is true, is the edge of the yellow box also controlled by the signal?
In this case when I passed the green light the last vehicle from the previous phase of the signals was exiting the far side of the boxed junction. It then stopped just outside the yellow box blocking my exit. It was for this reason that I stopped after passing the green signal but before entering my side of the yellow box.
What I am not clear about is this.
Had I realised the signals on my side had changed back to red, if they had, should I have waited on the edge of the yellow box until they changed to green again in my favour, or, having already passed the signal on green was it okay to proceed as my exit was now clear?