If you mean the white lamp under the bumper then yep, it's a work light and doesn't work off any of the dash switches I have on my ex-AA.
I've never got round to tracing the wires for mine - must do that sometime !!
As for the dash switches, make sure the connections haven't come off the back of the bulbs... Or could be blown bulbs that need replacing... Pop the switches out and have a mooch.