Rapid sidelights

I have a 2013 Rapid saloon. The sidelights suddenly stopped working. The bulb failure indicator is lit, but the numberplate lights are on and the audible indicator sounds when the door is open!. I've checked all the fuses under the dashboard, all OK. All other lights work normally. I recently worked on the electrics under the boot lid, but this doesn't seem to tie up with the fault. Any ideas?