Hi Ben. I was aware of this late war economy system and the description on Rob's site clears it up in my head. I thought you meant the push button as a headlamp dip switch. But of course it switches from pilot bulb to headlamp bulb. This would then save the cost of an ammeter and about two meters of cable.
Obviously to do the test, you must first back up to a wardrobe mirror. :smile:
At some point they even deleted the press button Ron
I seem to remember discussing a theory about the completely blank panel, it allowed a replacement standard headlamp to be fitted to an early machine with the switch panel in the tank.
it seems that the test (test-off-T-H) switch under the seat i have is working the same way as a 4 position (off-T L H) switch would that is fitted in the headlamp, im thinking mine has the wrong switch cam fitted, im trying to find a picture of one to se what it should look like,