ohh, ermm, what setting do i use on the meter? the net has brung up a few different results, cheers 
Two points
Is the Cabby a genuine RS. Don't remember there being a cabby option.
The battery light should come on when the ignition is switched on. This provides the tickle to the alternator. If the light is not present then the alternator won't be getting the tickle it needs so it won't charge.
Cheers
PD
if speedo fails let me know and i'll have a look.i wouldnt even know where to begin trying to sort that light out