Hazard Warning Light

Noticed tonight, the hazard warning light on my 95 XJ6VP (on the clock panel) stays lit all the time even when the dash lights are off (and the ignition is off). The flashers work perfectly when I press the button, and it flashes in sequence with the blinkers. I just wondering why the button (switch) is lit all the time even when the lights & ignition is off.

Richard