Firstly, the bus has not stopped for the crossing, it has stopped for the ambulance. If you look closely it has pulled up well short of the crossing and tight into the kerb, this is not the driving position. Since the whole length of the bus is in the zigzag area this can't be a bus stop (unless newham has enacted the laws bus drivers think exist) The road conditions were good and the ambulance was going at a speed which they could stop in time. And Lo, they did even if it was a bit rough for those on board The pedestrian upon hearing sirens (doubly so if a change of tone aproaching the hazard was used), should look very closely before crossing. If cars start pulling over to the side of the road that is a good clue that it is coming this way.