Spare main beam dashlight wire

There was an extra, bog standard, not a steering column switch, toggle switch on the steering column of my 90. It seemed to control t he headlight main beams.

Some tinkering with the actual dip switch showed it to be fairly knakkered, which explains the toggle switch (though for the effort of wiring up an additional switch why not just replace the dip switch?!)

So the toggle switch had a blue/red wire going to it and a blue/white so these aren't additinal wires, they#ve come from somewhere
looking at the workshop manual
the blue /red is the acc. wire for the main beams (goes from dip switch to the lights)
the blue/white is the dash light signal wire and also goes to the fusebox

I've successfully traced the blue/red that comes from the dip switch and found the connector the blue/red came from, so that's that wire back in the right place (I hope)

The blue/white, however, appears to be orphan. Tracing the blue white that comes off the dip switch disappears into the abyss that is "beyond the dash".
The blue/white coming off the dash light also disappears "beyond the dash"

Anyone got any idea where I find the point where the blue/white coming from the dip switch breaks out to the dash light (that's where this orphan wire should be living),I just can't find the bloody thing...