This is how the configuration was when I bought the Vehicle
 I Intend to fit a 70A relay across the Switch.

 
The land rover W/S manual shows an earth lead from No1 plug to the Engine 

All the tests I have done tell me that the Screwed section of the plug body does
not earth out the plug

 All the testing procedures show in the W/S manual [NOT Haynes – but the Rover one]
Show 2 connections one on the Knurled Nut, and the second below the ceramic isolating collar

 ??? Where do I earth these plugs out.???

Any ideas