I had a similar incident the other year with an American operator at LGW - apparently some crew who haven't operated to LGW before expect the red 'STOP' sign to come on when they are correctly parked. In my incident an accident was only averted by the quick response of the ground engineer pushing the emergency tit by the guidance controls.
Pity the authorities cannot get together and come up with ome international standard for positioning lights on aprons.