A scenario

[Distant]

You are approaching this box junction and traffic lights. http://g.co/maps/drjke

The lights are green on approach, but change just as you enter the box junction. Due to the length of your vehicle it is not possible to stop before the stop line without overhanging the box. Do you continue through the light, or stop at the line with the back of the vehicle in the box?

[Pontoneer]

Assuming you cannot stop before the entrance on the left , which the box junction is there to keep clear , I would say that it is worse to run a red light than to overhang the box junction , especially given the layout here .

A better solution would be advance the stop line to a position before the entrance , and give the premises a traffic light of their own .

[Zeeky]

There is no prohibition from stopping on the box so long as it isn't caused by the presence of stationary traffic. If you are in a car you wont obstruct the entrance so there should be no issue with stopping at the lights. It's safe, legal and considerate.

[R0G]

Car or small van no problem

Artic on a DSA test - fail if stopped and blocking grid and fail if jumping lights !!