Trying to remember the name of the show...two guys buy a car and fix it up for profit, they did a P38 a while back and showed pretty well how to apply the lettering. They did the front lettering, but I'm sure same applies to rear.
The letters are already spaced out on the tape, you just have to get it centred right.
Hopefully someone else has a better memory than me! :doh:
Wheeler Dealers, that was it....thanks for helping me out there Wammers!
YouTube - ‪Wheeler Dealers s08e03 - Range Rover P38 part 3/3.avi‬‏
I like the bit where he goes on about sourcing the right parts to keep it all the same, and then sticks a pre-2000 headlight on it!