Thanks - earthing one of them would have been my next guess, but nice to have it confirmed
But I'd have to cut one of them... I probably didn't explain it very well, but one of the SWC wires coming out of the little white 12-way connector which goes into the head unit then proceeds into pin A2 on the ISO block, which then obviously connects to the two corresponding connectors in the Rover, so I don't have an end to connect to anything
Hang on, will get a pic - so the two SWC wires come out of connector A. One of them is available for connection to the wheel switches, but the other one goes off into the ISO connector...