All right. Now that we have the basic pattern of the back part, it’s time to work on the adaptations. We will begin with the lower part of the back. It might be worth noting here, that in the original, there is indeed a seam running horizontally behind the belt (which is not usual for an Ulster), due to the pleats we are going to take a look at in a minute.
First of all, and easiest to do, we take away a bit of the width at the waist line. Based on the analysis of lots of pictures (check out the RPF link in my links collection, RayR, who actually owns the coat, has uploaded several, extremely helpful pictures there, also specifics as to measurements etc. He’s a HERO!) I’m taking away 2 cm from the side. The new point T2 needs to be connected to L2 by a simple straight line to get our new side line.
I have decided to make the center box pleat 3 cm deep at the waist and widen it to 6,5 cm at the hem.
The dotted red line left of ouf center back (blue) shows the later position of that pleat. On the right hand side I have extended the pattern accordingly, i.e. I added the strip necessary for the pleat twice since it will be folded under (at the right-hand dotted line) and back towards the center.
You can see here why I warned you about not starting that close to the right edge of your paper…
Therefore, point P1 is 6 cm from T1. Both will later be placed on top of each other.
And at the hem, this looks accordingly, point P1b is 13 cm from L1.
The side pleat begins on the waist line 10 cm from the center (T1-P2 = 10 cm) which means that in my pattern it’s 9,5 cm from the side (which matches exactly the specs RayR took from his coat).
At the hem, the pleat ends 12 cm both from center and side (in P2b).
I had some discussion (with myself) about the nature of that pleat; and I am still not sure it really does widen at all towards the hem. But to be on the safe side I will make it 3 cm deep at the waist and 5 cm at the hem (instead of the continuous 4 cm I started out with). I marked the position of the pleat with another dotted red line.
Since we cannot extend the pattern to include the side pleat (as I did with the center box pleat) without cutting the paper up, we’ll do that later when we copy the pieces onto silk paper.
Now, this is what my finished master pattern for the lower part of the back looks like: