@wingpig - I think it was the fact that we didn't pull in to the side, doff our helmets and let the real traffic past, once the lights changed.
ASZ's are OK, only if, once moving, you don't then impede traffic.
So add another pre-requisite to Magnatom's ASZ list - only to be used by fast cyclists, or cyclists that can cope with close passes, never to be used by slow, primary positioned cyclists...
Robert