Land Rover Repair: Light Steering at Speed, suspension bushings, landrover discovery

Question
I drive a 1994 V8 automatic landrover discovery. Recently I have noticed that above 70mph the steering has become light and unresponsive with 1/2 inches play on either side. Control at this speed has become difficult. Is there A specific reason for this and how do I rectify the fault.
PS. I recently topped up the steering fluid with 1/2 inches of standard fluid - would this affect handling?

Answer
You should check all the steering ball joints - there are four.  Check the tire pressures - 30 in front, 38 in back.  Check your alignment. Check the suspension bushings for play. Finally, look for play in the box.  You should find the answer in one of those areas.