That'll mean the bulb is on all the time rather than flashing to show the indicators are on.Is the bulb not working an MOT failure?
Why not just wire the bulb independently so it lights up when you turn on the ignition. Run a wire from one side of the bulb to any ignition switched live.
Connect the other side of the bulb to an earth.
rustychassis any pict's of your switch
the circuit is ground through the none energised indicator lamps which is the same as series one / two and series 3 Land Rovers later defenders (300TDI &TD5) have warning lamps for both side and use a ground return for each lampView attachment 207595