Leyland DAF Horse Box?

My Leyland DAF Roadrunner has developed an electrical problem. As I was trying to start it today, suddenly all the ingition lights went off and it wouldn't turn the starter motor. The head lights still work including hazards.
If i fiddle around with the with the wires and keep turning the key, the ignition lights sometimes come back on but when I turn the key to start, all lights go off.
What could the problem be?