I doubt they'd use a series diode. A 230V bulb connected to 400V through a diode would still be severely overrun and probably wouldn't lasy very long.
Be interesting to hear the response from the manufacturer, but by bet is on a small transformer.
Is Electrolux a popular make in Sweden? Their base in the U.K. is near to where I grew up; they're most closely associated with refrigerators here.
