Recently incurred annoying situation with n/s headlamp switching off and on intermittently
Not what you want on long, windy and dark country roads.

[i]Eventually[/i] found the cause.
Inside the headlamp, there is a considerable wiring loom on which there is a crimped joint
supplying two lamps. The manufacturer had strapped the flying leads to the bulb terminals
too close, so every time the headlamp turned, it broke the strands.

Easily fixed (hopefully) by cutting the wires back and using "choc block" to rejoint.
So far - two weeks later - no problem.

Not the car, but the part which was bought in by Ford