Well Ive just changed the loom and all fixed - MIL off car running fine.
Got a good discount from a Land Rover dealer in Kent cost £32.34. The new loom is shorter than the original so has to go directly to the ECU box. Probably the proper way to install this would be to drill a hole in the side of ECU box and install thru there. I made a small cut in the top of one of the rubber shrouds carrying cables into the box and inserted the new cable there instead, wrapping the shroud in insulating tape.
The 3 new wires went into a plug at the front of the box. This is the third plug from the right - I removed the other two to enable access to the plug to be worked on.
The plug you need has one black block and one grey block. Each block is numbered with 4 rows of 13. The two blocks can be slid from the holder to enable fitting the new wires shich are a push fitting.
pin 20 is brown/green
pin 33 is blue/black
pin 35 is white/yellow