Hi, I think the british gas wireless system is a rebranded Drayton unit, you can find some manuals on their website here http://www.draytoncontrols.co.uk/Digistat3RFProgrammableRoomThermostat.aspx
Go to bottom of page and select brochures, instructions and download.
Select Digistat+2RF & Digistat+3RF Commissioning Guide for info on the WR1 system, the bad news is that it tells you very little about what the lights mean, just what they should be when your setting it up, it does tell you how to retune the units, the rest of the info goes into detail about the thermostatic controls.
dai vaughan
December 2010