2006 Renault Modus lost dipped beam

I usually leave my dipped lights on 24/7, although they stay on when ignition is switched off they go off when drivers door opened. Due to a recent eye condition my wife has turned chauffeur but stays in car if she can. I showed her how to turn lights off: now dipped beam won't come back on. If I play with switch and ignition I can get them on but lose them before I drive off. Any ideas?
For completeness: All other lights work and dipped will come on if I flash main (including indicator bulb) but go off on starting engine.