No need for a yellow box as you should not be stopping in the Pedestrian crossing (although I suspect a lot of motorists ignore the rules).
From the Highway Code:
5. Pedestrian crossings (191 to 199)
191
You MUST NOT park on a crossing or in the area covered by the zig-zag lines. You MUST NOT overtake the moving vehicle nearest the crossing or the vehicle nearest the crossing which has stopped to give way to pedestrians.
Laws ZPPPCRGD regs 18, 20 & 24, RTRA sect 25(5) & TSRGD regs 10, 27 & 28
192
In queuing traffic, you should keep the crossing clear.
Quite agree regarding traffic light phases, there are some on the northern road out of Gloucester which are equally unfriendly to pedestrians.