I started by making a paper template of the modified wall with the new doorway for the kitchen to the rear and started laying down paddle pop sticks in a staggered pattern. (Sorry my picture is upside down, the door way is the L shape to the right.:p )
You can just see faintly that I have two lines drawn on the paper to the left. They were my stagger lines for my wood planks. I did this so the pattern wouldn't be completely random and messy. I also kept me on track.
Here it is in situ. It is not fitting very well around the top of the doorway at the moment, so I will need to cut a little away. But you get the idea. ;)
I will update when it's painted.
Here's the wall painted. I've switched the door to the kitchen back to the front because I want to use the space under the stairs for furniture and the piece I wanted to put there didn't fit with the door at the rear. I'll use the above wall upstairs between the bedroom and the living room.