First, I worked on the faux pockets, including adding the facing for the pockets. You can see where I did some pattern matching on the inner pocket.
Then created the faux pocket flaps that covered the inner pocket matching (but I know that they are there!) The faux pockets had to be handstitched down in certain locations to keep it from flopping or gaping.
In addition to the faux pockets, the left side had a patch pocket with a box pleat. I tried to match the stripes as best as possible (despite the fact that there's a dart underneath the pocket, while adding the box pleat. There was a lot of pinning and re-pinning.
Once the patch pocket was added, it was matter of lining up stripes on the refashioned pocket flap.
After the pockets were added, I hand-basted each of the pockets closed so that they wouldn't gape or distort the fronts while I was sewing the rest of the outfit. Then, I could start to add the interfacing and padding.
For the interfacing, I used standard horsehair canvas (not really made out of horsehair). I prefer horsehair canvas versus fusible interfacing mostly because I tend to find fusible interfacing (while extremely convenient) sometimes makes fabric too stiff and doesn't lay naturally. (I have been told that there is fusible hymo, which I haven't tried yet, but I didn't have time to order some and try them out.)
First, I took the horsehair and quilt stitched the padding (just some wool felt) to it, then basted it to the front along the edges. The padding helps fill out certain "hollows" in the human body, such as the shoulder hollow, so that the jacket lies in a straight line from the shoulder down. Some people require more padding than others. I also cheated and machine quilted the padding to the interfacing, which is an acceptable way of doing it, but most bespoke tailors will hand stitch the padding.
However, I couldn't get away from hand-stitching. I had to padstitch the lapel area to the front fabric piece, which took several hours to complete as it requires carefully catching only one thread of the fashion fabric (so that it doesn't show) and stitch it to the interface. (And there was at least once where I had to rip out all of my work because I had placed the tailor padding in-between the horsehair and fabric and didn't notice...)
Afterwards, I added a twill tape along the lapel roll line after cutting along that faint blue line. I handstitched the twill to either side of the horsehair.
The twill tape acts as a hinge to help the collar fold over and lay correctly; otherwise the horsehair will try to "unfold" the lapel to an open position.
Only after completing all of these steps could I then cut out the side and back pieces.