Discovery/RR Power Steering Leaks
 

First thing to check is the clamps, the clamps on the Discovery and even the Earlier Range Rovers are cheap junk sadly. Just replacing the clamps with a cheap upgrade will fix PS leaks most of the time. The hoses are not much better and may require the low pressure hoses to be replaced.

If hoses are bad go by your local auto parts store and gets some good oil resistant hose and replace as need (with good clamps). If the PS box is leaking you can attempt to fix with Lucas PS or Lucas Transmission Fix (both are hydraulic fluid bases so no major differences.

Add the bottle of Lucas and hope this fixes things.