I had a fault on my Disco where the key in ignition chime did not work. Check your rear Brake or tail light bulbs, Right hand side If I remember correctly.
If it's blown then that could be your answer as they are on the same circuit.
The rear windows are caused by a dry solder joints on the ECU board, it's an easy fix, pull the ECU board out and you should see probably 3 dry solder joints, its a very common fault!. Just hit them with a solder iron tip and re insert it back into the ECU case. No need to buy a new one.