Turn off the juice at the fusebox, remove both cables from the switch and temporarilly tape them with some insulation tape, so they don't touch each other, or anything else.
Turn the power supply back on and see if the light comes on. If it does, you can rule out the switch and call in a sparky to find out wtf is going on!
Turn the power supply back on and see if the light comes on. If it does, you can rule out the switch and call in a sparky to find out wtf is going on!