I had also been warned by the Land Rover dealer during a complete checkup of the vehicle that these leads were not original Land Rover parts. Since I needed to replace lead #1, I decided to replace the entire system with all original Land Rover parts.
I ordered the following from the local Land Rover dealer:
- 4 Spark plugs
- 4 Ignition leads
- 1 Rotor Cap
- 1 Main lead
- 1 Rotor Arm
- 1 Rotor plate
Oddly enough the correct order can't be directly found in the Haynes nor the official Land Rover workshop manual. I later found out that the cylinder numbering starts with cylinder #1 at the cam belt side and stops with #4 on the rotor cap side. The numbering for the ignition leads on the rotor cap can be found on the rotor cap itself.
I was told by the dealer that gapping of the spark plugs was not necessary and that there was a risk of breaking the plugs doing so, so I did not bother.
Video of the engine running with the new leads (pretty boring actually...):